UNIT IV
Consciousness, circadian rhythms, dreams, sleep
CIRCADIAN RHYTHMS
• When do you feel most alert and energetic?
• regular fluctuations in our bodily processes and in consciousness
over time- biological rhythms
• Many of these fluctuations occur over the course of a single day and
are therefore known as circadian rhythms (from the Latin words for
“around” and “day”).
• Other fluctuations occupy shorter periods of time
• for instance, many people are aware of fluctuations in their alertness, energy,
and moods over the course of a day
• Researchers spend extended periods isolated from natural light,
temperature fluctuations, or other stimuli that could signal the time
of day
• early researchers used caves
• Nathaniel Kleitman conducted the first cave experiment in 1938
• He and a graduate student spent 32 days isolated from the outside
world in Mammoth Cave, Kentucky.
• The researchers imposed a 28-hour cycle on themselves consisting of
ten hours of work, nine of leisure, and another nine hours of sleep.
• Bedtime shifted four hours later each day during the Mammoth Cave
study.
• Despite the alternative schedule and the absence of external cues,
Kleitman found that body temperature continued to fluctuate in an
approximately 24-hour cycle
• existence of an endogenous clock
• an internal mechanism to keep biological cycles synchronized with
natural day-night rhythms independent of external cues
• Circadian rhythms (i.e., circa 24 hours long) are endogenous in
nature, and regulate our physiology, metabolism and behavior.
• They also synchronize an organism to periodically recurring
environmental conditions, such as light–dark or temperature cycles
(Abraham et al., 2010).
• Individuals differ in their circadian preferences, known as
morningness and eveningness, and popularly defined as
chronotypes.
• Chronotypes are divided into three types:
• morning, neither and evening type
• Chronotype influences physiological and cognitive functions
underlying a circadian rhythm.
• The biological parameters are that of body temperature and
melatonin and cortisol hormones and cognitive performance
parameters are that of attention, memory and executive function
task.
• Ana Adams (2015) suggests that chronotype as compared to
subjective characteristics such as personality has much potential in
explaining individual functioning.
• Empirical studies report that these types show differences in
acrophase or the alertness curve,
• while the early hour is associated with Morning type (M type) and late hours
of the day with the Evening type (E type) (Kerkhof, 1998).
• M types typically reached their peak performance levels in working
memory in the morning hours
• E types reach their peak performance levels in the afternoon or early
evening (Hasher, Goldstein, & May, 2005).
• Results reported by Smith et al. (2002) who investigated the curve of
alertness in a research where the authors presented a 12-items scale
– the Preference Scale (2002): extreme M types showed greater
alertness in the morning hours compared to extreme E types.
• The summary that we can draw from these studies is that arousal and
alertness vary for both the types −─ morningness and eveningness.
• Most people are aware of fluctuations in their alertness, energy, and
moods over the course of a day
• Research findings indicate that such shifts are closely related to
changes in underlying bodily processes (e.g., Moore-Ede, Sulzman, &
Fuller, 1982).
• Daily cycles occur in the production of various hormones, core body
temperature, blood pressure, and several other processes.
• Large individual differences in this respect exist
• In addition, circadian rhythms seem to shift with age; as people grow
older, their peaks often tend to occur earlier in the day.
• Cyclic fluctuations in basic bodily functions—and in our subjective
feelings of alertness—are related to task performance.
• In general, people do their best work when body temperature and
other internal processes are at or near their personal peaks.
• However, this link appears to be somewhat stronger for physical tasks
than for mental ones–especially tasks that require considerable
cognitive effort.
• If bodily processes, mental alertness, and performance on many tasks change
regularly over the course of the day,
• we possess some internal biological mechanism for regulating such changes
• In other words, we must possess one or more biological clocks that time
various circadian rhythms.
• While there is not as yet total agreement on the number or nature of these
internal clocks
• Existing evidence points to the conclusion that one structure—the
suprachiasmatic nucleus (SCN), located in the hypothalamus—plays a key role
in this respect.
• Interestingly, it appears that individual cells in this structure “tick”—keep track
of time.
• On the contrary, it responds to light, which serves as a zeitgeber
(German for “time giver”).
• Morning light resets our internal biological clock, synchronizing it with
the outside world.
• Our biological clock (and that of many other species) seems to
operate on a twenty-four-hour cycle.
• Thus, if it were not reset each day, our internal biological rhythms
would get farther and farther out of synch with the world around us.
Dreams ......
• Inner theatre
• Mental activity
• dramatic aspect of sleep
• it is jumbled, vivid, enticing, sometimes disturbing images that fill our
sleeping minds
• Basic facts
• Does everybody dream?
• Yes. Not all people remember dreaming, but EEG recordings and related data indicate
that everyone experiences REM sleep.
• How long do dreams last?
• Many people believe that dreams last only an instant, but in fact they seem to run on
“real time”: The longer dreams seem to last, the longer they really are (Dement &
Kleitman, 1957).
• Do dreams foretell the future?
• There is no scientific evidence for this widespread belief.
• Do dreams express unconscious wishes?
• there is no convincing scientific evidence for this view.
Dreams: The psychodynamic view
• that dreams express unconscious wishes or impulses
• influence was greatly increased by Sigmund Freud,
• dreams provide a useful means for probing the unconscious–thoughts,
impulses, and wishes that lie outside the realm of conscious experience.
• In dreams, we can give expression to impulses and desires we find
unacceptable during our waking hours
• we can dream about
• gratifying illicit sexual desires
• about inflicting painful torture on persons who have made us angry–thoughts
we actively repress during the day.
• Freud carefully analyzed the dreams of his patients,
• gained important insights into the causes of their problems
• Reports of these experiences as a therapist, was fascination filled with
conviction, that many people quickly accepted Freud’s claims
• Not supported by convincing scientific evidence.
• Freud provided no clear-cut rules for interpreting dreams and no way
of determining whether such interpretations are accurate.
• In view of these facts, few psychologists currently accept the view
that dreams offer a unique means for exploring the unconscious.
Dreams: the physiological view
• Dreams are simply our subjective experience of what is, in essence,
random neural activity in the brain.
• Such activity occurs while we sleep simply because a minimal
amount of stimulation is necessary for normal functioning of the
brain and nervous system
• Dreams then simply represent efforts by our cognitive systems to
make sense out of this random neural activity (Foulkes, 1985;
Hobson, 1988).
• A logical extension of this view suggests that the activity of which we
try to make sense is not actually random; rather, it occurs
• primarily in the two systems of the brain that are most active when we are
awake–the visual system and the motor system.
• As this view suggests, dreams are usually silent but are filled with
visual images
• And although many dreams contain images of movement, few
persons report experiencing smells, tactile (touch) sensations, or
tastes in their dreams (Carlson, 1999)
Dreams: The cognitive view
• Cognitive systems’ efforts to interpret neural activity while we sleep.
• This perspective, proposed by Antrobus (1991), suggests that two
facts about REM sleep are crucial to understanding the nature of
dreams:
• (1) During REM sleep, areas of the cerebral cortex that play a role in waking
perception, thought, and regulation of motor processes are highly active
• (2) yet at the same time, during REM sleep there is massive inhibition of
input from sensory systems and muscles (these are suppressed).
• As a result, Antrobus (1991) reasons, the cortical structures or systems that normally
regulate perception and thought have only their own activity as input.
• The result is that this activity forms the basis for the imagery and ideas in dreams.
• Since they represent interpretations of neural activity by our own brain, dreams reflect
aspects of our memories and waking experience.
• Convincing evidence for this connection between dreams and important events in our
lives is provided by the fact that many persons attempting to make important changes
in their own behavior–for example, to quit smoking or drinking–report having dreams
of absent-minded transgression–DAMIT dreams for short (e.g., Gill, 1985).
•
• In such dreams, people suddenly notice that they have carelessly or
absent-mindedly slipped into the habit they wish to break–they are
smoking or drinking without having planned to do so.
• This realization leads to feelings of panic or guilt in the dream.
• In many cases the dreamers awake at that point, feeling quite
disturbed.
• such dreams is positively related to success in breaking the habits in question
(e.g., in giving up smoking) (Hajek & Belcher, 1991).
• So this kind of dream, at least, does seem to be related to important
events in our daily lives