AO1: Ultradian Rhythms
1.
Sleep Stages
An ultradian rhythm exists within the sleep portion of the daily wakefulness and sleep cycle. There are
5 stages of sleep.
Stage 1
N
R
E
M
Stage 2
Stage 3
Slow
Wave
Sleep
REM Sleep
Stage 4
Stages 1 and 2 are light sleep, characterised by a change in the
electrical activity in the brain. As you become more relaxed your
brain waves switch from beta waves, to alpha waves. These are
slower, more regular and have a greater amplitude.
As you go to sleep, the waves slow down further, they have a
greater wave frequency. This is called a theta wave. Theta
waves are accompanied by bursts of activity (increased wave
frequency called sleep spindles) and increased wave amplitude
(k complexes).
Stages 3 and 4 are characterised by even slower delta waves,
these stages are called slow wave sleep (SWS). In this stage, it is
very hard to wake someone up. Most of the body’s physiological
repair work is undertaken and important biochemical processes
take place such as the production of growth hormones.
In REM sleep there is fast, desynchronised EEG activity
resembling the awake brain.
These cycles continue
throughout the night
with the SWS period
getting shorter and
REM periods getting
slightly longer as the
night progresses. Each
sleep cycle is about 60
minutes in early
infancy, increasing to
90 minutes during
adolescence.
2.
Basic Rest-Activity Cycle
The 90-minute sleep cycle is itself located within a 24-hour circadian cycle, so it would make
sense to find that this 90-minute ‘clock’ was also ticking throughout the day. It is called the
basic rest-activity cycle (BRAC). Freidman and Fisher (1967) observed eating and drinking
behaviour in a group of psychiatric patients over periods of 6 hours. They detected a clear 90minute cycle in eating and drinking behaviour.
PSYA3 Learning Table 2: Ultradian and Infradian Rhythms
The ultradian rhythm spans less than a day, one example is the bi-daily temperature rhythm.
AO2 – Supporting/Contradictory Evidence
AO2 - MAID
:-/ Mixed support for REM and dreaming sleep
: Reductionism vs Holism
P: One assumption of REM sleep is that it is associated with dreaming sleep.
P: One issue with the research into ultradian rhythms such as the sleep cycle is that it is reductionist.
Nevertheless, there is mixed support for this assumption.
E: This is because it reduces the complex nature of the sleep cycle purely down to ultradian rhythms, for
E: For example, Dement and Kleitman (1957) were the first to demonstrate this
example 5 biologically determined stages including REM (characterised by delta waves) and Non-REM sleep
link. They woke participants up at the times when their brain waves were
(characterised by alpha, beta and theta waves).
characteristic of REM sleep and found that participants were highly likely to
E: Although this allows for the complex behavior of sleep cycles to be understood and studied in a scientific
report dreaming. However they also found that dreams were recorded outside
manner (i.e. measuring sleep in terms of brain waves); it fails to account for other factors that may affect sleep
REM sleep and that sleepers, when awoken in REM sleep, were not always
and sleep cycles. For example, the importance of the role of exogenous zeitgabers such as light has been
dreaming.
demonstrated by Campbell and Murphy (1998) who found that if you shine light on the back of participants’
E: While, this supports the idea that REM is paradoxical sleep (as brain and eyes
knees, this shifted their sleep patterns.
are active but body paralysed); it is not necessarily the only stage where
L: Consequently, this means that the research into ultradian rhythms in sleep is arguably flawed because it does
dreaming can occur. It may be that theta waves, accompanied by bursts of
not offer a full account of the sleep cycle behavior. Instead, a more holistic view should be considered that
activity may also be conducive to dreaming in NREM sleep. Furthermore,
encompasses both biological and exogenous cues when researching ultradian rhythms such as the sleep cycle.
Hobson and McCarley (1977) proposed that dreams are just a psychological
read-out of the random electrical signals typical of REM sleep.
: Methodological Issue: Ecological Validity
L: Although, the importance of the REM/dream link is that it potentially provides
P: A major flaw with sleep research conducted in a controlled environment is that it lacks ecological validity.
a way to identify when someone is dreaming and therefore might provide
E: This is because the research is carried out in an artificial and uncomfortable environment. Furthermore,
theorists with a way of explaining dreaming; the link still remains unclear.
participants are required to wear electrodes to measure brain wave activity as well as sleep whilst being
recorded.
:-/ Mixed support for REM and dreaming sleep
E: Although this allows researchers to isolate, manipulate and control for variables, it means that the sleep they
P: One issue with research into the nature of REM sleep is that there is mixed
are investigating may be qualitatively or quantitatively different from sleep in the participants’ natural
support for the assumption that it is dreaming sleep.
environment.
E: This is because some studies have reported figures as high as 70% for the
L: As a result, findings from studies such as Dement and Kleitman (1957) cannot be generalised to outside the
percentage of reported dreams during NREM sleep.
laboratory setting. Furthermore, this reduces support for the assumption that REM sleep is dreaming sleep.
E: Foulkes (1967) attributed this difference to confusion as to what constitutes a
dream. Vague, dream-like experiences or muddled thoughts have sometimes
been incorrectly categorised as dreams.
L: Consequently, this casts doubt the internal validity of Dement and Kleitman’s
research into the nature of REM sleep, as they may not have been accurately
measuring dreaming sleep. As a result, the credibility of this research, and
research like it can be questioned.
P: One strength of research into ultradian rhythms is that support for the BRAC has
been provided by Maxim & Storrie (1979).
E: They found that the BRAC varied between species and is dependent on metabolic
rate. Smaller animals which typically have faster metabolic rates have shorter BRACs.
E: For example, this ultradian rhythm in a cat is only 20 minutes long. It can be
demonstrated by observing any continuous behavior such as self-stimulation of the
brain. The cat’s continuous activity shows a dip every 20 minutes. A similar pattern
which varies from 40 – 85 minutes can also be detected in rhesus monkeys.
L: As a result, this research boosts the credibility of other research into the BRAC as it
indicates reliable findings, particularly across species.
: Methodological Issues – Unrepresentative Sample
P: One issue with research into the basic rest-activity cycle is that there are methodological issues involved with it.
E: For example, Friedman and Fisher (1967) used an unrepresentative sample of psychiatric patients to investigate the
existence of the 90 minute clock outside of the sleep cycle to support the ultradian rhythm assumption.
E: This is an issue because psychiatric patients are likely to have heavily regulated eating and drinking times due to the
medication they would be prescribed. Furthermore, these times would be determined by their healthcare plan; and not if
they felt hungry or thirsty. This would clearly demonstrate a 90 minute cycle, regardless of their innate rest-activity cycle.
L: As a result, while the findings from Friedman and Fisher’s study do provide valuable insights into the existence of a 90
minute clock outside of the sleep cycle, the findings cannot be generalised to the wider population. As a consequence,
this reduces the credibility for the very existence of basic rest-activity cycle in ultradian rhythms.
The infradian rhythm has a period of more than one day but less than one year, such as the menstrual cycle in women.
P: One weakness of the research into the female menstrual cycle is that it does not
1.
Monthly Cycles
: Determinism vs Free Will
take into consideration the role of exogenous cues in the regulation of this
Female Menstrual Cycle
P: One issue with the menstrual cycle as an infradian rhythm is that it is arguably deterministic.
infradian
rhythm.
E: For example, Dr Dalton, a GP and pioneer researcher into Pre-Mentrual Tension (PMS) has often acted as an expert

Driven by fluctuating hormone levels.
E: Russell at al (1980) conducted a study in which daily sweat samples were
witness in real life crime trials. She argues that PMS is akin to a mental disorder and therefore individuals should not be

Its function is to regulate ovulation.
collected from one group of women and rubbed on to the upper lip of women in a
held responsible for their actions. This suggests that biological rhythms, such as the female menstrual cycle are beyond

The pituitary gland releases hormones (FSH & LH) which stimulate a follicle
second group. The groups were kept separate yet their menstrual cycles became
our control. It assumes that if a woman is suffering from PMS, she will behave illogically and irrationally.
in one ovary to ripen and egg and trigger the release of oestrogen.
synchronised with their individual odour donor.
E: However, the deterministic interpretation fails to take into account the evidence that we can ‘will’ our biological

The ruptured follicle starts to secrete progesterone which causes the lining
E: This suggests that the synchronization of menstrual cycles can be affected by
rhythms to change. For example, Born et al (1999) found that people who were told to wake up at earlier times of the
of the womb to prepare for a pregnancy by increasing its blood supply.
pheromones – chemicals which are released in, for example, sweat. Pheromones
night than usual had higher levels of the stress hormone ACTH (which contributes to the waking up process) than
act like hormones but have an effect on the bodies of people close by rather than

After two weeks, if there is no pregnancy, progesterone is reduced and this
normal at the designated time and they woke up earlier. Therefore this demonstrates the importance of free will in the
the body of the person producing them. This is an issue because the research into
causes the lining of the womb to be shed.
the female menstrual cycle describes this infradian rhythm in terms of the
regulation of biological rhythms such as the menstrual cycle and sleep wake cycle.
Male Rhythms
endogenous
systems
that
govern
it
(i.e.
the
release
of
hormones
under
the
control
L: As a consequence, the explanatory power of PMS as an infradian rhythm is reduced because there is

Empson (1977) conducted a study on male participants which involved
of the pituitary gland).
evidence to suggest that individuals have choice to act in a certain way. The fact that individuals have free
measuring body temperature and alertness levels.
L: As a result, the research into the female menstrual cycle only offers a partial
will over external cues that also affect our behavior, makes PMS an inadequate explanation overall.

These were measured over periods varying from 49 to 102 days.
explanation for the way in which it is regulated and as a result, this reduces the

The study found some evidence in males for a periodic variation of both
overall credibility of the research.
body temperature and subjective ratings of morning alertness, with a cycle
length of approximately 20 days.
P: A strength of research conducted into SAD is that support has been provided by
: Real Life Application: SAD
2.
Seasonal Affective Disorder (SAD)
Terman et al (1998).
P: A strength of the research into seasonal affective disorder (SAD) is that it has led to a deeper understanding of the role of
Infradian rhythms apply to behaviours that occur once a year. Some people suffer from a
E:
They
conducted
a
study
in
which
a
total
of
124
participants
(ages
18
–
65)
with
darkness in SAD. This has led to effective therapies, most notably phototherapy.
depressive condition called seasonal affective disorder (SAD). They become severely
SAD
took
part.
Over
3
weeks,
85
participants
received
daily
30
minute
exposures
to
E: Phototherapy used very strong lights in the evening and/or early morning to change levels of melatonin and serotonin. The
depressed in the winter months and recover during the summer.
bright lights from a box mounted above the head. Some had light therapy in the
lights are between 6,000 and 10,000 Lux, which is equivalent to full daylight; a 60 watt bulb produced 1000 lux. SAD sufferers
Research has shown that this is caused by a hormonal imbalance. Hormones melatonin
morning, others in the evening. The remaining participants sat for 30 minutes each
have reported that daily use of such boxes us enough to relieve them of their feelings of lethargy, depression and other related
and serotonin are secreted when it is dark; more darkness means more melatonin, and
morning in front of an apparatus called a negative ion generator, which emitted air
symptoms.
more melatonin means less serotonin (because melatonin is produced from serotonin).
ions. These treatments were placebos. They found that of those who received the
E: This suggests that the research has valuable real life application. As the effectiveness of phototherapy has been confirmed, this
Low levels of serotonin are associated with depressed.
morning light therapy, 60% showed marked improvements in SAD symptoms
supports the theory that SAD is caused by imbalances in melatonin and serotonin.
compared to 30% of those in the evening light condition. Winter depression eased
in only 5% of participants exposed to air ions.
E: This therefore provides support for the idea that SAD may be the result of
hormonal imbalances as exposure to bright lights would reduce production of
melatonin and serotonin.
L: As a result, this boosts the credibility for the research conducted into SAD.
L: As a result, this boosts the credibility of the research, giving it a high level of real life applicability.
P: Nevertheless, the effectiveness of phototherapy has been questioned.
E: Eastman et al (1998) found that a placebo condition (fake negative-ion generator) was less effective but 32% of participants did
improve with the placebo alone.
E: This suggests that the causes of SAD may not be as clear as first thought (if a placebo can alleviate the symptoms, then perhaps
it is not to do with hormonal imbalances in the first place).
L: As a consequence, this casts doubt over the credibility of the research into the effectiveness of phototherapy.