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Theories of sleep
- Sleep - a physical and mental
resting state where a person
becomes inactive and unaware
of the environment
- Restoration theory
- Oswald (1966) believed that the function
of sleep was to re-group our resources
after expending them during the day
- believed that REM was important
for brain growth, and SWS was
important for bodily growth
- believed that REM was important
for brain growth, and SWS was
important for bodily growth
- during the first year babies sleep
18/24 hours; age 5 an adult circadian
pattern is established, may be due to
environmental and maturation factors
- newborn infants spend half the 18 hours in
REM, adults spend 1/4 of the 18 hours in
REM; babies have to grow more
- newborn infants spend half the 18 hours in
REM, adults spend 1/4 of the 18 hours in
REM; babies have to grow more
- Sassin (1969) found that
when sleep-waking cycles are
reversed by 12 hours, the
release of GH is also reversed
- also suggested that sleep is an important way of
conserving neurotransmitters; through the day, the
amount of neurotransmitters in our bodies decreases;
REM sleep replenishes neurotransmitters
- Stickgold (2005) - REM important in the
consolidation of procedural memory,
SWS important for the consolidation of
semonic and episodic memory
- Jouvet (1967) - when a cat went into REM sleep
it's skeletal muscles relaxed, leading it to fall into
the water, waking it up; the more deprived of
REM sleep the cat was, the more attempts it
made to enter REM; the cat eventually died
- REM is necessary
for adequate brain
functioning
- however, cat
could've died
from stress
- REM is necessary
for adequate brain
functioning
- DJ Peter Tripp - stayed
awake for 201 hours;
started hallucinating and
getting paranoid
- Randy Gardner - stayed
awake for 260 hours;
displayed no significant
psychotic symptoms
- however, Randy
would've had
microsleeps (same
as normal sleep)
- however, Randy
would've had
microsleeps (same
as normal sleep)
- Randy Gardner - stayed
awake for 260 hours;
displayed no significant
psychotic symptoms
- Lavie (1984) studied a 20 y.o whose
head was injured by shrapnel; no
REM and this had no ill effects
- Oswald (1966) believed that the function
of sleep was to re-group our resources
after expending them during the day
- Evolutionary theory
- Energy conservation
- warm-blooded animals
need to expend a lot of
energy to maintain a
constant body temperature
- all activities use
energy and animals
with high metabolic
rates use even more
- hibernation theory
- sleep serves a purpose
of providing a period of
enforced inactivity
(using less energy)
- sleep serves a purpose
of providing a period of
enforced inactivity
(using less energy)
- however, Capellini (2008)
found a negative relationship
between metabolic rate and
sleep; doesn't support the
energy conservation theory
- warm-blooded animals
need to expend a lot of
energy to maintain a
constant body temperature
- Predator avoidance
- sleep is
constrained by
predation risk
- predators can 'afford'
to sleep for longer
- prey species must
remain vigilant so their
sleep time is reduced
- sleep is
constrained by
predation risk
- Waste of time
- Meddis (1975) - sleep may simply
ensure that animals stay still when
they have nothing better to do
- Siegel (2008) - being
awake may be more riskier
than sleeping as an animal
could get injured
- Meddis (1975) - sleep may simply
ensure that animals stay still when
they have nothing better to do
- Energy conservation
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