Running head: A PRIMER FOR MEDIA SCHOLARS 1 This is a post-print version. Sleep Research: A Primer for Media Scholars Article accepted for publication in Health Communication Please cite as: Exelmans, L., Van den Bulck, J. (ahead of print). Sleep Research: A Primer for Media Scholars. Health Communication. https://doi.org/10.1080/10410236.2017.1422100 A PRIMER FOR MEDIA SCHOLARS 2 Abstract The average amount of sleep people of all ages get has declined sharply in the past fifty years. The detrimental health effects of sleep deprivation are well documented and substantial. Even though electronic media use often takes place in the hours before sleep, the extent to which media use may interact with sleep is understudied and not well understood. Communication scholars are well-positioned to contribute in this area, as a systematic, theoretical understanding of the relationship between media and sleep is still lacking. This primer charts the state of knowledge on electronic media and sleep and explores possible next steps. First, we introduce the problem of sleep deprivation and describe the basic science of sleep with relevant terminology. Then, we review the research on electronic media and sleep and offer an agenda for research. A PRIMER FOR MEDIA SCHOLARS 3 “Technology has decoupled us from the 24-hour day to which our bodies evolved.” (Charles Czeisler). The Sleep Problem Studies have estimated that we sleep 1 to 2 hours less than 50 years ago (Bixler, 2009; Cappuccio & Miller, 2011). More than one in three (37.1%) adults are now sleeping less than 7 hours per night (Schoenborn & Adams, 2010), an amount at which physiological and neurobehavioral problems develop and become progressively worse under chronic conditions (Van Dongen, Maislin, Mullington, & Dinges, 2003). The National Sleep Foundation (Gradisar et al., 2013) reported that 6 out 10 Americans (13-64 years old) are not getting enough sleep to function properly. A study by Pallesen et al. (2008) showed an increase in sleep onset problems among teens between 1983 and 2005 and Matricciani, Olds, and Petkov (2012) found rapid declines in children’s sleep duration over the course of a century. In all, it appears that a growing number of people is struggling with sleep, facing sleep problems, or coping with chronic sleep insufficiency. The consequences of sleep loss can be far-reaching. It is estimated that around 20% of serious car accidents are connected to driver sleepiness; and fatigue induced occupational errors are thought to be partly responsible for major global disasters such as the Exxon Valdez oil spill or the nuclear reactor meltdown in Chernobyl (Institute of Medicine, 2006). The cumulative effects of chronic sleep deprivation stretch to a variety of physical and mental health consequences, including reduced memory function and learning ability, negative mood states, risk behavior, obesity, reduced immune response, hypertension, and cardiovascular disease (Luyster, Strollo, Zee, & Walsh, 2012; Strine & Chapman, 2005) . In sum, negative effects of poor sleep produce a ripple effect, by spreading to a wide range of health issues, resulting in an overall reduced quality of life and increased mortality (Grandner, Hale, Moore, & Patel, 2011). A PRIMER FOR MEDIA SCHOLARS 4 Given sleep’s pivotal role in health, research into the predictors of poor sleep has spiked over the past decades. There is mounting evidence that electronic media use contributes significantly to a shorter sleep duration, sleep disruption, longer sleep latency, and overall poorer sleep quality (Hale & Guan, 2015). While clearly an interdisciplinary topic, research on the effects of media use on sleep has mostly been conducted by sleep researchers. The involvement of communication scholars in this field can have a crucial impact on its advancement, as their theories and research methods are highly relevant for and transferrable to sleep research. Consequently, communication scholars have a potentially significant role to play in tackling the global epidemic of sleep insufficiency. The goal of this primer is to help bridge the gap between sleep medicine research and media studies. To that end, we will first describe the basic mechanics of sleep, introducing relevant vocabulary (that will be highlighted in bold). Next, we will briefly review the evidence linking media use to sleep and summarize the three most common explanations for these effects. Finally, we will outline an agenda for research on this topic, suggesting where the expertise of communication scholars is most valuable. Sleep: Basic Mechanics and Terminology What Is Sleep? Although sleep may seem like a biologically passive state, it involves a complex interaction of physiological processes (Luyster et al., 2012). In general, sleep is divided into two states: non-rapid eye movement (NREM) sleep (75-80% of total sleep time) and rapid eye movement (REM) sleep (20-25% of total sleep time). NREM sleep is divided into three stages, characterized by a progressive decrease in brain wave activity, eye movement, and heart rate. NREM stage 1 refers to sleep onset, a light stage of sleep often characterized as “drifting off”, taking up 5% of total sleep time. During stage 2 of NREM sleep, eye movement stops, conscious awareness of our surroundings fades, and brain waves slow down. In total, we spend 45-55% A PRIMER FOR MEDIA SCHOLARS 5 of our sleep time in stage 2. Stage 3 of NREM is called deep sleep or slow wave sleep, characterized by extremely slow brain waves (15-25% of total sleep time). Most of the recovery processes take place during this stage. When awakened during deep sleep, people feel groggy and disoriented for several minutes. During the last stage - REM sleep - muscles relax completely, heart rate and blood pressure increases and eyes move rapidly (20-25% of total sleep time). Information processing and memorization take places. Because of increased brain activity, we often dream during this stage. We repeat the sleep cycle of NREM and REM sleep 3-7 times per night, each cycle lasting 90-110 minutes. After each cycle, we approach wakefulness before drifting off to NREM 1 again. As the night progresses, the length of deep sleep (stage 3 NREM) decreases and REM sleep increases (Lee, 2016; Luyster et al., 2012; Markov, Goldman, & Doghramji, 2012). What Makes Us Sleep – Or Not? Sleep Regulation Processes The two-process model describes the timing and regulation of sleep and wakefulness as an interaction between the homeostatic and the circadian process. The homeostatic process refers to the need for sleep or sleep pressure, which increases the longer you stay awake. The homeostatic drive reaches its peak in the evening, decreases during sleep and is at its lowest upon awakening. People suffering from sleep shortage experience a greater homeostatic drive or a tendency to make up for lost sleep, typically resulting in shorter sleep latency and longer total sleep time. The popular term for the circadian process is one’s biological or internal clock, which regulates our circadian rhythm (circa = about; dian = day), i.e., all the biological variables that fluctuate in a cycle length of approximately 24 hours (Markov et al., 2012). Apart from the sleep-wake cycle, other variables that follow a circadian rhythm are one’s body temperature, heart rate, and hormonal regulation. While our circadian rhythm is intrinsic, meaning that it has an endogenous clock following a 24h cycle, it is also constantly synchronized to maintain that 24h cycle by obtaining information from the environment, a A PRIMER FOR MEDIA SCHOLARS 6 process called entrainment. Based on the information obtained from the environment, and its own endogenous circadian clock, the circadian system regulates the body’s sleep and wakefulness according to the time of the day Both processes interact to regulate sleep: the sleep pressure from the homeostatic drive increases throughout the day but is opposed by the circadian process, which sends alerting signals to let us stay awake. When night comes, the circadian process will abruptly stop sending the alerting signals, which allows the homeostatic sleep drive to take over, so sleep becomes possible (Gillette & Abbott, 2005; Luyster et al., 2012; Markov et al., 2012). How Much Sleep Do We Need? Sleep need varies strongly between individuals (Ferrara & De Gennaro, 2001). For example, it is well-documented that women have a greater sleep need than men and that sleep need declines with age (Hume, Van, & Watson, 1998). Some individuals may need significantly more or less sleep than the average and are categorized as long vs. short sleepers (Aeschbach et al., 2003). Chronotype, or the extent to which someone can be categorized as a morning or evening type (Roenneberg, Wirz-Justice, & Merrow, 2003), also influences our sleep habits. Morning and evening types differ in the timing of sleep and wakefulness (i.e., their circadian rhythm). Morning types (referred to as “larks”) have an advanced internal clock: they prefer earlier bedtimes and rise times, have a lower sleep need and are more alert upon awakening. Evening types (“owls”) prefer to stay up late, tend to have a greater sleep need, function at their peak later in the day, and have more irregular sleep schedules (Taillard, Philip, & Bioulac, 1999). Although the common recommendation of getting 8 hours of sleep per night represents the average sleep needed to function properly, “the amount of sleep we need to be at our best is as individual as the amount of food we need” (Ferrara & De Gennaro, 2001, p.4). A PRIMER FOR MEDIA SCHOLARS 7 Adolescents and Sleep: A Risk Group. Over the course of puberty, adolescents develop sleep phase delay: compared to children, they become increasingly inclined to stay up later at night and rise later in the morning. They thus evolve from larks to owls. This shift in sleep phase is attributed to a convergence of biological (such as delayed secretion of melatonin) and psychosocial (such as increased social pressure, academic demands, and autonomy) changes during puberty (Carskadon, 2011; Wolfson & Carskadon, 1998). However, concurrently with these changes, there is a societal pressure on adolescents’ sleep: school’s start times function as the predominant determinant of their rise time. School times cannot be delayed and often start even earlier for adolescents than for their younger counterparts. While they are biologically programmed to stay up later, school’s start times are incongruent with this shift. As a result, sleep time becomes compressed and there is little opportunity to make up for lost sleep, typically resulting in a tendency to compensate by sleeping late during the weekend, which disrupts the sleep cycle further (Carskadon, 1999, 2011; Wolfson & Carskadon, 1998). While sleep need generally declines with age, it does not change during adolescence: teens need approximately 9 hours of sleep, the same as children. Research nonetheless shows that they typically obtain only 6.5 to 7 hours of sleep, resulting in a severe and chronic sleep deprivation of nearly 2h per day (Calamaro, Mason, & Ratcliffe, 2009; Hysing, Pallesen, Stormark, Lundervold, & Sivertsen, 2013). In addition, other aspects of adolescent life, such as academic and social pressure and stress, often interact and also lead to irregular sleep patterns (Dahl & Lewin, 2002; Wolfson et al., 2003). In sum, adolescents experience a dramatic sleep change as they mature. Inadequate sleep during this developmental phase can have severe negative effects, both in the short and long term; marking adolescents as a particular risk group in sleep research. A PRIMER FOR MEDIA SCHOLARS 8 How Do We Measure Sleep? Analyses of sleep involve the assessment of multiple sleep indicators, which can be measured objectively or subjectively. The most important indicators are bedtime and rise time, sleep duration and sleep quality. However, to capture sleep duration accurately, additional parameters are needed, such as the time it takes to fall asleep (sleep latency) and the frequency and duration of night wakings (sleep disturbances) (Matricciani, 2013). Sleep quality is also partly dependent on a person’s sleep efficiency, a ratio of the time spent asleep to the time spent in bed, and is normally around 85-90% in a healthy population (Buysse, Reynolds, & Monk, 1989). The gold standard in the objective measurement of sleep is polysomnography (PSG). The “poly” in the word refers to the fact that PSG records various sleep parameters: the electrical activity in the brain, eye movements, respiration rate, cardiac activity and limb movements. Together, these indicators provide an accurate assessment of the diagnostic criteria needed to determine sleep disorders, but it requires special equipment and expert training. This method has excellent internal validity, but the fact that it is measured in the highly artificial setting of a sleep lab reduces its external validity for media research questions (Lee, 2016; Markov et al., 2012). Duration, type, access, content, and awareness of media use in a laboratory setting is likely to be very different from a typical evening spent at home. The second way of objectively measuring sleep is the use of actigraphy or ambulant monitoring. An actigraph or accelerometer is usually worn on the wrist and will estimate whether a subject is awake or asleep based on body movement. Actigraphy has proven to be reliable and valid in studying sleep in healthy populations and is far less invasive, cheaper, can be done at home, and makes longitudinal measurement possible. However, it also has some notable disadvantages. It has an oversensitivity of scoring nocturnal movements as wakefulness, thereby deflating the estimate of total sleep (Short, Gradisar, Lack, Wright, & A PRIMER FOR MEDIA SCHOLARS 9 Carskadon, 2012). Moreover, it cannot discern between various sleep stages or between sleep disorders, and becomes less reliable in clinical samples. So far, there is a large variety of actigraphs, but there are no device standards, standardized units of measurement or analytic methods, which make comparison across studies difficult. Therefore, the application is often limited to monitoring the circadian rhythm, studying sleep in samples where PSG is less feasible (such as infants or elderly people), monitoring treatment effects, and estimating habitual sleep patterns over time (Ancoli-Israel et al., 2003; Lee, 2016; Sadeh, 2011). In addition to these objective measurements, there exist a multitude of paper-based self-report assessments of sleep. A meta-analysis by Hale and Guan (2015) showed that 99% of studies on media and sleep rely on self-reports. There are several review studies on the various self-report sleep scales that are available for research (Devine, Hakim, & Green, 2005; Spruyt & Gozal, 2011). To measure habitual nighttime sleep, the Pittsburgh Sleep Quality Index (PSQI) (Buysse et al., 1989) is the most widely used (Lee, 2016). The measure has undergone extensive validation and can be used in both clinical and non-clinical samples. The PSQI integrates seven sleep components: sleep duration, subjective sleep quality, sleep latency, sleep efficiency, use of sleep medication, sleep disturbances, and daytime dysfunction. Both the sub scores on the components and the global score can be used in research settings. Although the PSQI is very user friendly for both researcher and respondent and can distinguish between patients and controls, it has received criticism too, for instance regarding its measurement sensitivity (the usual cut-off score to discern good from poor sleepers is argued to be too low), and that it does not pay sufficient attention to daytime experience (Carpenter & Andrykowski, 1998). It should therefore preferably by accompanied by a measure of fatigue, such as the Epworth Sleepiness Scale (Johns, 1991) or Flinders Fatigue Scale (Gradisar et al., 2007) . When interested in tracking one’s experience with sleep of having an indicator of the stability in sleep, sleep diaries are also valuable measurement tools. A PRIMER FOR MEDIA SCHOLARS 10 Comparison studies with diary data and objective sleep measures have shown that selfreports offer a valid way to measure sleep variables (Monk et al., 2003; Wolfson et al., 2003), and research concluded that diary data are superior to actigraphy when it comes to predicting fatigue (Short et al., 2012) Nonetheless, self-report measures of sleep also have their downsides, such as their vulnerability to recall bias (Hassan, 2005). It is also well-documented that insomniacs, for example, underestimate their sleep duration, a phenomenon called sleepmisperception (Harvey & Tang, 2013). Spruyt and Gozal (2011) have remarked that there is an abundance of self-report measures for sleep that has not undergone rigorous psychometric evaluation. There is, therefore, a big distinction between the use of published versus validated questionnaires, a subtle difference that may escape notice when reading journal articles or books. While sleep researchers tend to take comfort in objective sleep assessment tools, it can be argued that the subjective experience of sleep and fatigue may be at least as important, if not more important, than objective measures, at least for some issues (Pilcher, Ginter, & Sadowsky, 1997). This perspective is reflected in an increase in the use of subjective reports as the outcome variable (Ancoli-Israel et al., 2003). This is further supported by the fact that there are large individual differences in sleep need: one person will need 9 hours of sleep to feel rested whereas the next only needs 6 hours (Ferrara & De Gennaro, 2001). In sum, scholars have recommended, if the use of PSG is not feasible or advisable, to use actigraphy in concert with subjective data to obtain a full and accurate assessment of sleep (Lee, 2016; Sadeh, 2011). For complete self-reported research, it is advised to measure multiple parameters of sleep, including bedtime, sleep latency, rise time, night awakenings, sleep quality, and to separate weekdays from weekend days (Cain & Gradisar, 2010). A PRIMER FOR MEDIA SCHOLARS 11 What about sleep apps? In recent years, a staggering number of mobile phone apps have emerged that claim to accurately register sleep related data. Some of these provide digital diaries to monitor sleep habits (such as Sleep Journal or Yawnlog); while others track movement in bed to measure sleep and thus require people to keep their phone on the bed (such as Sleep Cycle or Sleep Bot). Van den Bulck (2014) argued that sleep apps have the potential to expand the field by introducing a cost-effective way to obtain an unprecedented access to sleep data. There is, however, a multitude of devices available and a lack of validation studies to assess whether sleep apps and other wearables can accurately and consistently assess sleep parameters. Given these limitations concerning the measurement validity of apps, sleep researchers have been wary of their use in research settings (Behar, Roebuck, Domingos, Gederi, & Clifford, 2013; Van den Bulck, 2014). Electronic Media & Sleep: State of the Art In addition to societal changes, such as longer working hours, shift work schedules, and the idea that sleep can be easily missed out on, sleep insufficiency is exacerbated by technology use (Bixler, 2009; Cappuccio & Miller, 2011). The shift towards poor sleep has coincided with technological revolutions that have intensified media usage. Total daily media use amounts to approximately 6 hours per day for 8-12 year olds and 9 hours per day for 13-18 year olds (Common Sense Media, 2015). . In addition, electronic media have gravitated towards our bedroom over the years (Bovill & Livingstone, 2001), which has been known to stimulate evening usage (Cain & Gradisar, 2010). In all, we devote as much time to our screens as we should be to sleeping. Over the past decade, a growing number of scholars have studied the interplay between electronic media and sleep. The most recent review study covered a total of 67 studies (Hale & Guan, 2015). While we cannot provide a comprehensive review of all the research in this area, A PRIMER FOR MEDIA SCHOLARS 12 we will attempt to give an overview of the main findings on electronic media and sleep and, most importantly, outline an agenda for future research. Readers who are interested in a more extensive review are redirected to the meta-analyses by Cain and Gradisar (2010) and Hale and Guan (2015). Electronic Media as Inhibitors of Sleep A poll by the National Sleep Foundation (2011) indicated that 95% of 1508 respondents (13-64 years old) used electronic media within the hour before bed. In another study, almost 70% of teens indicated that electronic media use was their final evening activity (Kubiszewski, Fontaine, Rusch, & Hazouard, 2013). The large majority of studies (90%) on electronic media document negative effects of media use on numerous sleep parameters, such as delayed bedtime (e.g., Kubiszewski et al., 2013; Oka, Suzuki, & Inoue, 2008; Woods & Scott, 2016), shorter sleep time (e.g., Arora, Broglia, Thomas, & Taheri, 2014; Paavonen, Pennonen, Roine, Valkonen, & Lahikainen, 2006), longer sleep latency (e.g., Dworak, Schierl, Bruns, & Strüder, 2007; King et al., 2013), increased daytime fatigue (e;g., Lemola, Perkinson-Gloor, Brand, Dewald-Kaufmann, & Grob, 2015; Li et al., 2007), and night awakenings and nightmares (Van den Bulck, 2004a; Van den Bulck, Çetin, Terzi, & Bushman, 2016). Such results have been replicated across media devices, and have been found in cross-sectional, longitudinal and experimental designs. The presence of media in the bedroom appears to exacerbate the problem: those with media in the bedroom report increased usage (Christakis, Ebel, Rivara, & Zimmerman, 2004), and sleep duration was significantly lower among teens who had four or more devices in their bedroom (National Sleep Foundation, 2014). Although variations in effects can be found across cultures based on the access to media and culturally related sleep problems (Owens, 2004), the negative effects of technology use on sleep are a worldwide phenomenon. A PRIMER FOR MEDIA SCHOLARS 13 Electronic Media as Facilitators of Sleep One of the most common reasons parents have reported for having a television in a child’s bedroom was the hope that it would help the child fall asleep (Rideout & Hamel, 2006). There has also been an increase in the development of content specifically designed to help children calm down and transition to sleep at the end of the day (Zimmerman, 2008). Significant proportions of adolescents (Eggermont &Van den Bulck, 2006), and adults (Exelmans & Van den Bulck, 2016b) have reported using various media as a sleep aid. Gooneratne et al. (2011) reported that the most common method of self-treating sleep problems among older adults was watching television and Harmat, Takacs, and Bodizs (2008) found that listening to relaxing classical music can reduce sleep problems in students. Overall, the few studies that have investigated the idea that media may also be beneficial for sleep, suggest that the practice of using media as a sleep aid appears to be counterproductive: those who report using media as a sleep aid, also report poorer sleep (Eggermont & Van den Bulck, 2006; Exelmans & Van den Bulck, 2016b). Underlying Mechanisms The existing research on electronic media and sleep has mostly focused on charting the effects, and less on investigating the underlying mechanisms that explain them. Cain and Gradisar (2010) summarized them in a framework that contains three explanations for the observed effects. (Blue) light. To attain optimal sleep quality and duration, the circadian clock is aligned with the sleep-wake cycle. Our internal circadian clock resides in the hypothalamus, just above the point where optic nerves cross, and, therefore, the most potent external time cue or “zeitgeber” (zeit = time; geber = giver) for this synchronization is light. The signals received by our internal clock are sent through various regions of the brain, including the pineal gland, which responds A PRIMER FOR MEDIA SCHOLARS 14 by reducing the output of melatonin. Melatonin is often called the sleep hormone, because its levels usually increase when darkness falls, making us sleepy. In addition, the internal clock will regulate our heart rate, body temperature, and arousal levels to attain an optimal sleep mood (Luyster et al., 2012; Markov et al., 2012). Exposure to artificial light may result in misalignment between the sleep-wake cycle and the internal clock. Exposure to light late in the day or early in the night will slow down the internal clock, creating a fluctuation rate that exceeds 24 h. Light exposure in the evening has been found to increase alertness and arousal levels, suppress melatonin production (Wood, Rea, Plitnick, & Figueiro, 2012), and induce phase delay in the circadian clock (i.e. delay sleep time) (Cajochen et al., 2011; Wood et al., 2012). The effects of light on the secretion of melatonin are acute and can extend for hours beyond the light exposure (Berson, Dunn, & Takao, 2002). Research highlights that the effects of light on melatonin output and alertness may vary depending on the (1) light level and spectrum, (2) duration of exposure, (3) size and proximity to the screen, and (4) type of task. Shortwave length or blue light is most disruptive to melatonin production. This is commonly the type of light emitted by media screens (Cajochen et al., 2011). Wood et al. (2012) observed melatonin suppression after 1h of using self-luminous tablets in young adults. They measured variations of light intensity during such usage, and found that certain tasks on tablets are more harmful to sleep than others. Chang and colleagues (2015) found that, compared to reading a printed book, reading a book on a light-emitting e-reader before bedtime decreased subjective sleepiness, suppressed melatonin production, prolonged sleep latency by 10 minutes, and impaired morning alertness. Overall, these results point at a phase delay of the circadian clock, associated with increased risk of developing chronic sleep deficiency, or sleep disorders such as delayed sleep phase disorder or sleep onset insomnia. A PRIMER FOR MEDIA SCHOLARS 15 Sleep displacement. To date, the most commonly reported effects of electronic media on sleep are delayed bedtime, prolonged sleep latency and decreased sleep duration (Cain & Gradisar, 2010). These findings support the displacement hypothesis, which postulates that the time spent using media replaces time that would otherwise be spent sleeping (Van den Bulck, 2000). An early explanation of this process used Kubey's (1986) concept of media use and unstructured time. Media use takes place during leisure time and has no predefined beginning or end points. Van den Bulck (2000) argued that unstructured activities are most likely to displace activities that are similarly unstructured, such as sleep. Indeed, the start and endpoint of sleep are largely a matter of choice, with the exception, perhaps, of sleep policing attempts by parents. As media use peaks before bedtime, sleep is vulnerable to displacement by the media (Cain & Gradisar, 2010; Van den Bulck, 2004b). According to Exelmans and Van den Bulck (2017a) sleep displacement has evolved into a two-step process. The first step of sleep displacement occurs when people postpone going to bed because they prefer spending time using the media. This is the most commonly used meaning of the concept. People are, however, using media increasingly often and for increasing amounts of time while already in bed. Consequently, people may not only be putting off going to bed, but also delaying going to sleep once in bed. In their survey among 338 young adults, there were almost 40 minutes between people’s bedtime (the time at which they went to bed) and what they referred to as shuteye-time (the time at which they decided to try to sleep). The authors defined this second stage of sleep displacement (i.e., between bedtime and shuteye time) as shuteye latency (Figure 1). Using customary self-reported sleep measures, half of their participants would have had to be categorized as having sleep onset insomnia (i.e., they were awake for longer than 30 minutes after going to bed). The study shows, however, that this particular group spent this time in bed on other activities than trying to go to sleep. Notably, A PRIMER FOR MEDIA SCHOLARS 16 media use was identified as an important driver of shuteye-latency: a considerable proportion of the behaviors people reported engaging in in bed involved media. In sum, the authors concluded that the fast-paced changes in media necessitate a continuous reevaluation and update of existing survey questions in light of new trends in both media consumption and sleep behavior (Exelmans & Van den Bulck, 2015, 2017a). It is worth noting that the displacement hypothesis so far appears to hold exclusively in young samples. For adults, research shows that media use is associated with later bedtimes, but also with later rise times, and that, consequently, sleep duration does not appear to suffer. This process is referred to as time-shifting. It has been hypothesized that many adults have more control over their daytime schedule, which allows them to adjust both their shuteye- and rise time to their media use (Custers & Van den Bulck, 2012; Exelmans & Van den Bulck, 2014, 2016a). [FIGURE 1 AROUND HERE] Arousal. Violent and sexual content are as omnipresent in the media as they have ever been (Brown et al., 2006; Huesmann & Taylor, 2006). It has been shown that exposure to such content may induce excitement, fright, and stress reactions in children (Harrison & Cantor, 1999). The heightened arousal resulting from this exposure may be associated with difficulties falling asleep or poor sleep quality. Paavonen et al. (2006) reported that children who had viewed adult-targeted programs had a significantly higher risk of having sleep problems. A more recent study showed that violent daytime media exposure was associated with increased sleep problems, while this was not true for nonviolent daytime media use (Garrison, Liekweg, & Christakis, 2011). Viewing frightening content may coincide with having nightmares and night wakings, thus reducing sleep quality (Van den Bulck, 2004a; Van den Bulck et al., 2016). An intervention study by Garrison and Christakis (2012) found that young children whose A PRIMER FOR MEDIA SCHOLARS 17 parents had replaced violent media content with prosocial content reported improved sleep during follow-up. While there are only a limited number of studies taking into account the content of the media consumption, they suggest that the type of content may exert a significant impact on sleep quality, presumably through its effect on arousal. Agenda for Research Identifying Sleep Correlates of Types of Media & Usage Styles The topic of media and sleep covers a wide range of effects, given the wide range of devices and outcome variables. While there is now a considerable body of research on the effects of television, video games, and the internet, more recently introduced media such as smartphones and social networking sites have received less attention. It has been hypothesized that interactive media are more detrimental than “passive” media (Dworak et al., 2007; Gradisar et al., 2013). In part this is because social interaction capabilities mean that the devices have the potential to re-engage the user, even at night, when that user has decided to stop using them (Arora et al., 2014; Van den Bulck, 2003; Woods & Scott, 2016). The likelihood of displacing sleep in one user could also be higher when the termination of media use is partly dependent on another user at the other end of the communication. In all, the literature remains inconclusive on (1) which aspects of sleep are affected most by media use and (2) whether some sleep parameters are more affected by some media than others (Cain & Gradisar, 2010). Few studies so far have considered differences in media usage styles. Although mediamultitasking is a well-known topic in media research, it has received scant attention in sleep research. Calamaro and colleagues (2009) referred to a multitasking index in their study, but merely divided the time spent on various media by the time frame they were interested in. As such, the effects of simultaneously using different media devices have not yet been covered. In addition, the research regarding the effects of television viewing on sleep has yielded inconsistent findings (Hale & Guan, 2014) leading Bartel and colleagues (2015) to conclude A PRIMER FOR MEDIA SCHOLARS 18 that television was not a significant risk factor for sleep. The practice of television viewing has, however, undergone tremendous changes, that warrant a timely update of its measurement strategy in sleep research. Binge viewing effects on sleep, for instance, are a particular concern, considering the prevalence of consuming television in drenches rather than drips (Matrix, 2014). One study reported that binge viewing frequency was associated with poorer sleep quality, a relationship that was fully mediated by increased cognitive pre-sleep arousal (Exelmans & Van den Bulck, in press). Excessive or compulsive usage of media or so-called media addictions are also understudied topics. Finally, there could be merit in looking at the differential impact of work-related vs. recreational media use. Improving Measurement of Media Use Sleep research has focused predominantly on the frequency and duration of media usage when predicting the effects on sleep. To chart and understand the processes that are involved in the interaction between media use and sleep, a number of refinements should be considered. First, measures of media use should include when and where those media were used, because research shows nightly or in-bed media use has a stronger impact on sleep than overall media use (Exelmans & Van den Bulck, 2016a; Lemola et al., 2015; Woods & Scott, 2016). Second, while researched in an only limited number of studies (37% according to Hale and Guan, 2015), researchers should also study the social context of use. It can be hypothesized that a partner, parent, or child likely co-determine the termination of media usage or the timing of lights out. Third, little is known about differences in effects of media use depending on the content. Relaxing, (negatively or positively) arousing, or frightening types of content are likely to have a different effect on sleep outcomes. Moreover, in the era of streaming services and digital television, content is hyper-personalized and viewers are increasingly exposed to sophisticated narrative structures that are aimed at tying the viewer to the screen (Jenner, 2014, 2015). For social media or smartphones, there is virtually no research differentiating between the various A PRIMER FOR MEDIA SCHOLARS 19 activities done on the screen or active vs. passive usage of a social networking site. Fourth, we found only two studies that have examined the role of media engagement in predicting the effects on sleep: Smith, Gradisar, King, and Short (2017) demonstrated that increased flow significantly predicted bedtime delay among gamers and Woods and Scott (2016) found that those who were more emotionally invested in social media use experienced poorer sleep quality. It would be interesting to study the association between arousal originating from increased investment in media use (i.e., flow, transportation, fear of missing out), and pre-sleep arousal. Fifth, a recent study by Exelmans and Van den Bulck (2017b) led to unexpected results when taking into account media habits. Strong media habits appeared to prevent bedtime delay. More research on habit formation, habit strength, regarding the same and other media would further advance our knowledge of the processes leading to media displacement and time shifting. Six, based on the findings regarding the effect of blue light emitted by screens, researchers could look at the technical characteristics of the device such as the proximity, size and color composition of the screen. In all, developing a systematic understanding of the characteristics in media usage patterns that are most harmful to sleep could benefit the development of targeted interventions. Increasing Diversity in Research Samples Most studies on the relationship between media use and sleep behavior have been conducted among children and adolescents, which is unsurprising. In addition to being a risk group for sleep deprivation, children and teens are far more preoccupied with media than adults are assumed to be. It seems that adolescents are being set up to fail and become stuck in a cycle of dysregulation where their unhealthy sleep behavior stimulates increased media usage and vice versa. The particular concerns over the disruptive effects of media on sleep aimed at young children and adolescents are therefore certainly justified. A PRIMER FOR MEDIA SCHOLARS 20 However, this reasoning should not imply that studies among adults are unjustified or less worthwhile. 90% of people aged 13-64 yrs old use technology around bedtime (Gradisar, Wolfson, Harvey et al., 2013). For example, the proportion of video gamers has been found to diminish with age, yet the average gamer is not an adolescent, but an adult (between 30 and 35 years old). The frequency of gaming even increases with age (Lenhart, Jones, & Macgill, 2008). It would be wrong to assume that the potential effects of video games are therefore an issue in adolescents only. Similarly, it has been hypothesized that sleep quality and duration are progressively declining because our daytime schedules have become more crammed (Bixler, 2009). In comparison with children and teens, adults are juggling far more responsibilities, putting more pressure on their sleep. For instance, most research has looked at entertainment and leisure media. Work-related late night media use (such as e-mail) has not yet been studied in relation to sleep. Finally, adults are responsible for their own sleep schedule, while children’s sleep is often being watched over by their parents. Given these arguments and the fact that sleep varies highly depending on age, findings from young samples should not be extrapolated to adults (or vice versa) without further research. Most research is conducted in normative samples. There is merit in conducting research in clinical samples or in case-control studies that allow an accurate comparison of the functionalities of media use between normative and clinical samples. Media use, selection, and motives can be entirely different for those coping with a sleep problem. We have argued earlier in this paper that people often believe that media can be used as a sleep aid, and Mood Management Theory (Zillmann, 1988) supports the assertion that engaging in media may aid to recover from aversive mood, stress or strain. The use of media and their functionalities in clinical samples is an interesting avenue for future research. Clinical Relevance While the research on media and sleep has produced mostly significant findings, the question that often remains unanswered is whether and to what extent these findings are A PRIMER FOR MEDIA SCHOLARS 21 clinically relevant. For example, one study found that each additional hour of video gaming significantly delayed bedtime by 6.9 minutes and rise time by 13.8 minutes. While video gaming was related to more daytime fatigue, but it was not clear whether this delay also coincided with other noticeable health impairment (Exelmans & Van den Bulck, 2014). There are some starting points in the literature, nonetheless. King et al. (2013) found that prolonged violent video gaming (150 min) led to a 7% decrease in adolescents’ sleep efficiency score, a reduction that categorized these gamers below the established cut-off score (85%) used to identify sleep disorders such as insomnia. Oka et al. (2008) found that those who played video gaming or used the internet before bedtime slept two hours longer on weekend nights than on weeknights, , a discrepancy designated as clinically significant by the American Academy of Sleep Medicine (2005). To date, experimental research that determines whether reductions in media use or other evidence-based interventions can clinically improve sleep is extremely rare. Explore Causality Issues Most studies on media and sleep have relied on cross-sectional data. Some scholars therefore wonder whether the relationship between media and sleep might also be reversed (sleep difficulties lead to more media use) or even be bidirectional (i.e. media use has a negative effect on sleep, which is associated with increased media use). Results from longitudinal studies are mixed. Johnson, Cohen, Kasen, First, and Brook (2004) indicated that television viewing (>3h per day) during adolescence was associated with a significantly higher risk of having sleep problems during early adulthood and a two-wave study by Nuutinen, Ray, and Roos (2013) found that computer use, television viewing and the presence of media in the bedroom reduced sleep duration in children. A 3-year longitudinal study by Tavernier & Willoughby (2014) among university students, however, found that media use was an outcome of sleep problems instead of the reverse. They explained these unexpected effects by hypothesizing that the relationship between media use and sleep quality evolves across the life span. The results of A PRIMER FOR MEDIA SCHOLARS 22 Johnson et al. (2004) suggested a positive effect of reduced media use at age 14 on reduced sleep problems at age 16, but no effect of reduced media use at age 16 on reduced sleep problems at age 22. Research on the use of media as sleep aid emphasized the necessity of a longitudinal design to ascertain whether those who use electronic media to aid sleep may be even more tired if they did not do so. In sum, more longitudinal studies are needed to examine the temporal or cyclical relationship between media and sleep (Hysing, Stormark, Jakobsen, & Lundervold, 2015). Conclusion Sleep and media use both compete for a similar slice of our time. More and more, one cannot increase without limiting the time available for the other. The growing availability, portability, and even wearability of today’s “old” and “new” media exacerbate the issues. At the crossroads where media uses and effects research and sleep medicine meet, fascinating new insights await for both disciplines. A PRIMER FOR MEDIA SCHOLARS 23 References Aeschbach, D., Sher, L., Postolache, T. T., Matthews, J. R., Jackson, M. A., & Wehr, T. A. (2003). A longer biological night in long sleepers than in short sleepers. Journal of Clinical Endocrinology and Metabolism, 88, 26–30. https://doi.org/10.1210/jc.2002020827 American Academy of Sleep Medicine. (2005). The international classification of sleep disorders diagnostic and coding manual. Westchester, IL: American Ancoli-Israel, S., Cole, R., Alessi, C., Chambers, M., Moorcroft, W., & Pollak, C. P. (2003). The role of actigraphy in the study of sleep and circadian rhythms. Sleep, 26, 342– 392. Arora, T., Broglia, E., Thomas, G. N., & Taheri, S. (2014). Associations between specific technologies and adolescent sleep quantity, sleep quality, and parasomnias. Sleep Medicine, 15, 240–247. https://doi.org/10.1016/j.sleep.2013.08.799 Bartel, K. A., Gradisar, M., & Williamson, P. (2015). Protective and risk factors for adolescent sleep: A meta-analytic review. Sleep Medicine Reviews, 21, 72–85. https://doi.org/10.1016/j.smrv.2014.08.002 Behar, J., Roebuck, A., Domingos, J. S., Gederi, E., & Clifford, G. D. (2013). A review of current sleeps screening applications for smartphones. Physiological Measurement, 34, R29-46. https://doi.org/10.1088/0967-3334/34/7/R29 Berson, D. M., Dunn, F. A., & Takao, M. (2002). Phototransduction by retinal ganglion cells that set the circadian clock. Science, 295, 1070–1073. https://doi.org/10.1126/science.1067262 Bixler, E. (2009). Sleep and society: An epidemiological perspective. Sleep Medicine, 10, S36. https://doi.org/10.1016/j.sleep.2009.07.005 A PRIMER FOR MEDIA SCHOLARS 24 Bovill, M., & Livingstone, S. M. (2001). Bedroom culture and the privatization of media use. In M. Bovill, & S.M. Livingstone (Eds). Children and Their Changing Media Environment: A European Comparative Study, (pp.179–200). Mahwah, NJ: Lawrence Erlbaum Associates. Brown, J. D., L’Engle, K. L., Pardun, C. J., Guo, G., Kenneavy, K., & Jackson, C. (2006). Sexy media matter: Exposure to sexual content in music, movies, television, and magazines predicts black and white adolescents’ sexual behavior. Pediatrics, 117, 1018–1027. https://doi.org/10.1542/peds.2005-1406 Buysse, D. J., Reynolds, C., & Monk, T. (1989). The Pittsburgh Sleep Quality Index: A new instrument for psychiatric practice and research. Psychiatry Research, 28, 193–213. https://doi.org/http://dx.doi.org/10.1016/0165-1781(89)90047-4 Cain, N., & Gradisar, M. (2010). Electronic media use and sleep in school-aged children and adolescents: A review. Sleep Medicine, 11, 735–742. https://doi.org/10.1016/j.sleep.2010.02.006 Cajochen, C., Frey, S., Anders, D., Späti, J., Bues, M., Pross, A., … Stefani, O. (2011). Evening exposure to a light emitting diodes (LED)-backlit computer screen affects circadian physiology and cognitive performance. Journal of Applied Physiology, 110, 1432–1438. https://doi.org/10.1152/japplphysiol.00165.2011 Calamaro, C. J., Mason, T. B. A., & Ratcliffe, S. J. (2009). Adolescents living the 24/7 lifestyle: Effects of caffeine and technology on sleep duration and daytime functioning. Pediatrics, 123, e1005-10. https://doi.org/10.1542/peds.2008-3641 Cappuccio, F. P., & Miller, M. A. (2011). Is prolonged lack of sleep associated with obesity? BMJ, 10–12. https://doi.org/10.1136/bmj.d3306 A PRIMER FOR MEDIA SCHOLARS 25 Carpenter, J. S., & Andrykowski, M. A. (1998). Psychometric evaluation of the Pittsburgh Sleep Quality Index. Journal of Psychosomatic Research, 45, 5–13. https://doi.org/10.1016/S0022-3999(97)00298-5 Carskadon, M. A. (1999). When worlds collide: Adolescent need for sleep versus societal demands. Phi Delta Kappan, 80, 348–353. Carskadon, M. A. (2011). Sleep in adolescents: The perfect storm. Pediatric Clinics of North America, 58, 637–647. https://doi.org/10.1038/jid.2014.371 Chang, A., Aeschbach, D., Duffy, J. F., & Czeisler, C. A. (2015). Evening use of lightemitting eReaders negatively affects sleep, circadian timing , and next-morning alertness. Proceedings of the National Academy of Sciences, 112, 1232–1237. https://doi.org/10.1073/pnas.1418490112 Christakis, D. A., Ebel, B. E., Rivara, F. P., & Zimmerman, F. J. (2004). Television, video, and computer game usage in children under 11 years of age. The Journal of Pediatrics, 145, 652–656. https://doi.org/10.1016/j.jpeds.2004.06.078 Custers, K., & Van den Bulck, J. (2012). Television viewing, internet use, and self-reported bedtime and rise time in adults: Implications for sleep hygiene recommendations from an exploratory cross-sectional study. Behavioral Sleep Medicine, 10, 96–105. https://doi.org/10.1080/15402002.2011.596599 Dahl, R. E., & Lewin, D. S. (2002). Pathways to adolescent health: Sleep regulation and behavior. The Journal of Adolescent Health, 31, 175–84. Retrieved from http://www.ncbi.nlm.nih.gov/pubmed/12470913 Devine, E. B., Hakim, Z., & Green, J. (2005). A systematic review of patient-reported outcome instruments measuring sleep dysfunction in adults. PharmacoEconomics, 23, 889–912. https://doi.org/10.2165/00019053-200523090-00003 A PRIMER FOR MEDIA SCHOLARS 26 Dworak, M., Schierl, T., Bruns, T., & Strüder, H. K. (2007). Impact of singular excessive computer game and television exposure on sleep patterns and memory performance of school-aged children. Pediatrics, 120, 978–85. https://doi.org/10.1542/peds.2007-0476 Eggermont, S., & Van den Bulck, J. (2006). Nodding off or switching off? The use of popular media as a sleep aid in secondary-school children. Journal of Paediatrics and Child Health, 42, 428–33. https://doi.org/10.1111/j.1440-1754.2006.00892.x Exelmans, L., & Van den Bulck, J. (2014). Sleep quality is negatively related to video gaming volume in adults. Journal of Sleep Research, 24, 189–196. https://doi.org/10.1111/jsr.12255 Exelmans, L., & Van den Bulck, J. (2015). Technology and sleep: How electronic media exposure has impacted core concepts of sleep medicine. Behavioral Sleep Medicine, 13, 439–441. https://doi.org/10.1080/15402002.2015.1083025 Exelmans, L., & Van den Bulck, J. (2016a). Bedtime mobile phone use and sleep in adults. Social Science & Medicine, 148, 93–101. https://doi.org/10.1016/j.socscimed.2015.11.037 Exelmans, L., & Van den Bulck, J. (2016b). The use of media as a sleep aid in adults. Behavioral Sleep Medicine, 14, 121–133. https://doi.org/10.1080/15402002.2014.963582 Exelmans, L., & Van den Bulck, J. (2017a). Bedtime, shuteye time and electronic media: Sleep displacement is a two-step process. Journal of Sleep Research, 26, 363-370. https://doi.org/10.1111/jsr.12510 Exelmans, L., & Van den Bulck, J. (in press). Binge viewing, sleep and the role of pre-sleep arousal. Journal of Clinical Sleep Medicine. A PRIMER FOR MEDIA SCHOLARS 27 Exelmans, L., & Van den Bulck, J. (2017b). “Glued to the tube”: The interplay between selfcontrol, evening television viewing, and bedtime procrastination. Communication Research. https://doi.org/10.1177/0093650216686877 Ferrara, M., & De Gennaro, L. (2001). How much sleep do we need? Sleep Medicine Reviews, 5, 155–179. https://doi.org/10.1053/smrv.2000.0138 Garrison, M. M., & Christakis, D. A. (2012). The impact of a healthy media use intervention on sleep in preschool children. Pediatrics, 130, 492–9. https://doi.org/10.1542/peds.2011-3153 Garrison, M. M., Liekweg, K., & Christakis, D. A. (2011). Media use and child sleep: The impact of content, timing, and environment. Pediatrics, 128, 29–35. https://doi.org/10.1542/peds.2010-3304 Gillette, M. U., & Abbott, S. M. (2005). Basic mechanisms of circadian rhythms and their relation to the sleep/wake cycle. In D. P. Cardinali & S. R. Pandi-Perumal (Eds.), Neuroendocrine Correlates of Sleep/Wakefulness (pp. 19–40). Springer US. Gooneratne, N. S., Tavaria, A., Patel, N., Madhusudan, L., Nadaraja, D., Onen, F., & Richards, K. C. (2011). Perceived effectiveness of diverse sleep treatments in older adults. Journal of the American Geriatrics Society, 59, 297–303. https://doi.org/10.1111/j.1532-5415.2010.03247.x Gradisar, M., Ph, D., Lack, L., Richards, H., Hon, B. P., Harris, J., & Gallasch, J. (2007). The Flinders Fatigue Scale: Preliminary psychometric properties and clinical sensitivity of a new scale for measuring daytime fatigue associated with insomnia. Journal of Clinical Sleep Medicine, 3, 722–728. Gradisar, M., Wolfson, A. R., Harvey, A. G., Hale, L., Rosenberg, R., & Czeisler, C. A. (2013). The sleep and technology use of Americans: Findings from the National Sleep A PRIMER FOR MEDIA SCHOLARS 28 Foundation’s 2011 Sleep in America Poll. Journal of Clinical Sleep Medicine, 9, 1291–1299. https://doi.org/10.5664/jcsm.3272 Grandner, M. A., Hale, L., Moore, M., & Patel, N. P. (2011). Mortality associated with short sleep duration: The evidence, the possible mechanism and the future. Sleep Medicine Reviews, 14, 191–203. https://doi.org/10.1016/j.smrv.2009.07.006.Mortality Hale, L., & Guan, S. (2015). Screen time and sleep among school-aged children and adolescents: A systematic literature review. Sleep Medicine Reviews, 21, 50–58. https://doi.org/10.1016/j.smrv.2014.07.007 Harmat, L., Takacs, J., & Bodizs, R. (2008). Music improves sleep quality in students. Journal of Advanced Nursing, 62, 327–336. https://doi.org/10.1111/j.13652648.2008.04602.x Harrison, K., & Cantor, J. (1999). Tales from the screen: Enduring fright reactions to scary media. Media Psychology, 1, 97–116. https://doi.org/10.1207/s1532785xmep0102_1 Harvey, A. G., & Tang, N. (2013). (Mis)perception of sleep in insomnia: A puzzle and a resolution. Psychological Bulletin, 138, 77–101. https://doi.org/10.1037/a0025730.(Mis)Perception Hassan, E. (2005). Recall bias can be a threat to retrospective and prospective research designs. The Internet Journal of Epidemiology, 3, 1–11. https://doi.org/10.5580/2732 Huesmann, L. R., & Taylor, L. D. (2006). The role of media violence in violent behavior. Annual Review of Public Health, 27, 393–415. https://doi.org/10.1146/annurev.publhealth.26.021304.144640 Hume, K. I., Van, F., & Watson, A. (1998). A field study of age and gender differences in habitual adult sleep. Journal of Sleep Research, 7, 85–94. A PRIMER FOR MEDIA SCHOLARS 29 Hysing, M., Pallesen, S., Stormark, K. M., Lundervold, A. J., & Sivertsen, B. (2013). Sleep patterns and insomnia among adolescents: A population-based study. Journal of Sleep Research, 22, 549–556. https://doi.org/10.1111/jsr.12055 Hysing, M., Stormark, K. M., Jakobsen, R., & Lundervold, A. J. (2015). Sleep and use of electronic devices in adolescence: Results from a large population-based study. BMJ Open, 5, 1–8. https://doi.org/10.1136/bmjopen-2014-006748 Institute of Medicine. Sleep Disorders and Sleep Deprivation: An Unmet Public Health Problem. Washington, DC: The National Academies Press; 2006. Jenner, M. (2014). Is this TVIV? On Netflix, TVIII and binge-watching. New Media & Society, , 1–17. https://doi.org/10.1177/1461444814541523 Jenner, M. (2015). Binge-watching: Video-on-demand, quality TV and mainstreaming fandom. International Journal of Cultural Studies, 20, 304-320. https://doi.org/10.1177/1367877915606485 Johns, M. (1991). A new method for measuring daytime sleepiness: the Epworth Sleepiness Scale. Sleep, 14, 540–545. Retrieved from http://epworthsleepinessscale.com/wpcontent/uploads/2008/12/a-new-method-for-measuring-daytime-sleepiness-theepworth-sleepiness-scale2.pdf Johnson, J. G., Cohen, P., Kasen, S., First, M. B., & Brook, J. S. (2004). Association between television viewing and sleep problems during adolescence and early adulthood. Archives of Pediatrics & Adolescent Medicine, 158, 562–568. https://doi.org/10.1001/archpedi.158.6.562 King, D. L., Gradisar, M., Drummond, A., Lovato, N., Wessel, J., Micic, G., … Delfabbro, P. (2013). The impact of prolonged violent video-gaming on adolescent sleep: An experimental study. Journal of Sleep Research, 22, 137–43. https://doi.org/10.1111/j.1365-2869.2012.01060.x A PRIMER FOR MEDIA SCHOLARS 30 Kubey, R. (1986). Television use in everyday life: Coping with unstructured time. Journal of Communication, 36, 108–123. https://doi.org/10.1111/j.1460-2466.1986.tb01441.x Kubiszewski, V., Fontaine, R., Rusch, E., & Hazouard, E. (2013). Association between electronic media use and sleep habits: An eight-day follow-up study. International Journal of Adolescence and Youth, 19, 395–407. https://doi.org/10.1080/02673843.2012.751039 Lee, D. R. (2016). Teaching the world to sleep. Psychological and behavioural assessment and treatment strategies for people with sleeping problems and insomnia. London: Karnac Books. Lemola, S., Perkinson-Gloor, N., Brand, S., Dewald-Kaufmann, J. F., & Grob, A. (2015). Adolescents’ electronic media use at night, sleep disturbance, and depressive symptoms in the smartphone age. Journal of Youth and Adolescence, 44, 405–418. https://doi.org/10.1007/s10964-014-0176-x Lenhart, A., Jones, S., & Macgill, A. R. (2008). Adults and video games. Pew internet project data memo. Li, S., Jin, X., Wu, S., Jiang, F., Yan, C., & Shen, X. (2007). The impact of media use on sleep patterns and sleep disorders among school-aged children in China. Sleep, 30, 361–367. Luyster, F. S., Strollo, P. J., Zee, P. C., & Walsh, J. K. (2012). Sleep: A health imperative. Sleep, 35, 727–34. https://doi.org/10.5665/sleep.1846 Markov, D., Goldman, M., & Doghramji, K. (2012). Normal sleep and circadian rhythms. Sleep Medicine Clinics, 7, 417–426. https://doi.org/10.1016/j.jsmc.2012.06.015 Matricciani, L. (2013). Subjective reports of children’s sleep duration: Does the question matter? A literature review. Sleep Medicine, 14, 303–311. https://doi.org/10.1016/j.sleep.2013.01.002 A PRIMER FOR MEDIA SCHOLARS 31 Matricciani, L., Olds, T., & Petkov, J. (2012). In search of lost sleep: Secular trends in the sleep time of school-aged children and adolescents. Sleep Medicine Reviews, 16, 203– 11. https://doi.org/10.1016/j.smrv.2011.03.005 Matrix, S. (2014). The Netflix effect: Teens, binge watching, and on-demand digital media trend. Jeunesse: Your People, Texts, Cultures, 6. Monk, T. H., Buysse, D. J., Kennedy, K. S., Pods, J. M., DeGrazia, J. M., & Miewald, J. M. (2003). Measuring sleep habits without using a diary: The Sleep Timing Questionnaire. Sleep, 26, 208–12. Retrieved from http://www.ncbi.nlm.nih.gov/pubmed/12683481 National Sleep Foundation. (2014). 2014 Sleep in America Poll: Sleep in the modern family. Washington, DC. Nuutinen, T., Ray, C., & Roos, E. (2013). Do computer use, TV viewing, and the presence of the media in the bedroom predict school-aged children’s sleep habits in a longitudinal study? BMC Public Health, 13, 684. https://doi.org/10.1186/1471-2458-13-684 Oka, Y., Suzuki, S., & Inoue, Y. (2008). Bedtime activities, sleep environment, and sleep/wake patterns of Japanese elementary school children. Behavioral Sleep Medicine, 6, 220–233. https://doi.org/10.1080/15402000802371338 Owens, J. A. (2004). Sleep in children: Cross-cultural perspectives. Sleep and Biological Rhythms, 2, 165–173. https://doi.org/10.1111/j.1479-8425.2004.00147.x Paavonen, E. J., Pennonen, M., Roine, M., Valkonen, S., & Lahikainen, A. R. (2006). TV exposure associated with sleep disturbances in 5 - to 6-year-old children. Journal of Sleep Research, 15, 154–61. https://doi.org/10.1111/j.1365-2869.2006.00525.x Pallesen, S., Hetland, J., Sivertsen, B., Samdal, O., Torsheim, T., & Nordhus, I. H. (2008). Time trends in sleep-onset difficulties among Norwegian adolescents: 1983--2005. A PRIMER FOR MEDIA SCHOLARS 32 Scandinavian Journal of Public Health, 36, 889–895. https://doi.org/10.1177/1403494808095953 Pilcher, J. J., Ginter, D. R., & Sadowsky, B. (1997). Sleep quality versus sleep quantity: Relationships between sleep and measures of health, well-being and sleepiness in college students. Journal of Psychosomatic Research, 42, 583–96. Rideout, V., & Hamel, E. (2006). The media family: Electronic media in the lives of infants, toddlers, preschoolers and their parents. Menlo Park, CA: Kaiser Family Foundation. Rideout, V. (2015). The common sense census: Media use by tweens and teens. San Francisco, CA: Common Sense Media. Retrieved from https://www. commonsensemedia.org/research/the-common-sense-census-media-use-bytweens-andteens Roenneberg, T., Wirz-Justice, A., & Merrow, M. (2003). Life between clocks: daily temporal patterns of human chronotypes. Journal of Biological Rhythms, 18, 80–90. https://doi.org/10.1177/0748730402239679 Sadeh, A. (2011). The role and validity of actigraphy in sleep medicine: An update. Sleep Medicine Reviews, 15, 259–267. https://doi.org/10.1016/j.smrv.2010.10.001 Schoenborn, C.A., Adams, P.F. (2010) Health behaviors of adults: United States, 2005–2007. National Center for Health Statistics. Retrieved from https://www.cdc.gov/nchs/data/series/sr_10/sr10_245.pdf Short, M. A., Gradisar, M., Lack, L. C., Wright, H., & Carskadon, M. A. (2012). The discrepancy between actigraphic and sleep diary measures of sleep in adolescents. Sleep Medicine, 13, 378–384. https://doi.org/10.1016/j.sleep.2011.11.005 Smith, L. J., Gradisar, M., King, D. L., & Short, M. (2017). Intrinsic and extrinsic predictors of video gaming behavior and adolescent bedtimes : The influence of flow states, self- A PRIMER FOR MEDIA SCHOLARS 33 perceived risk-taking, device accessibility, parental-regulation of media and bedtime. Sleep Medicine, 30, 64-70. http://dx.doi.org/10.1016/j.sleep.2016.01.009 Spruyt, K., & Gozal, D. (2011). Pediatric sleep questionnaires as diagnostic or epidemiological tools: A review of currently available instruments. Sleep Medicine Reviews, 15, 19–32. https://doi.org/10.1016/j.smrv.2010.07.005 Strine, T. W., & Chapman, D. P. (2005). Associations of frequent sleep insufficiency with health-related quality of life and health behaviors. Sleep Medicine, 6, 23–27. https://doi.org/10.1016/j.sleep.2004.06.003 Taillard, J., Philip, P., & Bioulac, B. (1999). Morningness/eveningness and the need for sleep. Journal of Sleep Research, 8, 291–295. https://doi.org/10.1046/j.13652869.1999.00176.x Tavernier, R., & Willoughby, T. (2014). Sleep problems: Predictor or outcome of media use among emerging adults at university? Journal of Sleep Research, 23, 389–396. https://doi.org/10.1111/jsr.12132 Van den Bulck, J. (2000). Is television bad for your health? Behavior and body image of the adolescent “couch potato.” Journal of Youth and Adolescence, 29, 273–288. https://doi.org/10.1023/A:1005102523848 Van den Bulck, J. (2003). Text messaging as a cause of sleep interruption in adolescents, evidence from a cross-sectional study. Journal of Sleep Research, 12, 263–263. Van den Bulck, J. (2004a). Media use and dreaming: The relationship among television viewing, computer game play, and nightmares or pleasant dreams. Dreaming, 14, 43– 49. https://doi.org/10.1037/1053-0797.14.1.43 Van den Bulck, J. (2004b). Television viewing, computer game playing, and internet use and self-reported time to bed and time out of bed in secondary-school children. Sleep, 27, 101–104. A PRIMER FOR MEDIA SCHOLARS 34 Van den Bulck, J. (2014). Sleep apps and the quantified self: Blessing or curse? Journal of Sleep Research, 1–3. https://doi.org/10.1111/jsr.12270 Van den Bulck, J., Çetin, Y., Terzi, Ö., & Bushman, B. J. (2016). Violence, sex, and dreams: Violent and sexual media content infiltrate our dreams at night. Dreaming, 26, 271– 279. https://doi.org/10.1037/drm0000036 Van Dongen, H. P. A., Maislin, G., Mullington, J. M., & Dinges, D. F. (2003). The Cumulative cost of additional wakefulness: dose-response effects on neurobehavioral functions and sleep physiology from chronic sleep restriction and total sleep deprivation. Sleep, 26, 117–126. https://doi.org/10.1001/archsurg.2011.121 Wolfson, A. R., & Carskadon, M. A. (1998). Sleep schedules and daytime functioning in adolescents. Child Development, 69, 875–887. Wolfson, A. R., Carskadon, M. A., Acebo, C., Seifer, R., Fallone, G., Labyak, S. E., & Martin, J. L. (2003). Evidence for the validity of a Sleep Habits Survey for adolescents. Sleep, 26, 213–6. Wood, B., Rea, M. S., Plitnick, B., & Figueiro, M. G. (2012). Light level and duration of exposure determine the impact of self-luminous tablets on melatonin suppression. Applied Ergonomics, 44, 237–40. https://doi.org/10.1016/j.apergo.2012.07.008 Woods, H. C., & Scott, H. (2016). #Sleepyteens: Social media use in adolescence is associated with poor sleep quality, anxiety, depression and low self-esteem. Journal of Adolescence, 51, 41–49. https://doi.org/10.1016/j.adolescence.2016.05.008 Zillmann, D. (1988). Mood management through communication choices. American Behavioral Scientist, 31, 327–340. https://doi.org/10.1177/000276488031003005 Zimmerman, F. (2008). Children’s media use and sleep problems: Issues and unanswered questions. Research brief. Menlo Park, CA: Kaiser Family Foundation. A PRIMER FOR MEDIA SCHOLARS Figure 1 A. Traditional Sleep Displacement Model B. Exelmans & Van den Bulck (2017a) Sleep Displacement Model 35