Why do we sleep?
• Think about times in a persons life when they
might sleep LOTS……
• What might this tell us about why we need to
sleep?
Restoration Theory of Sleep
I can outline the restoration theory of sleep
E
C
A
I can describe some studies and case studies
that support or undermine the restoration
theory
I can evaluate theories using AIDS
O + E One or more functions of Sleep (24)
Restoration Theory of Sleep
Oswald (1980)
SWS enables your body to repair itself
REM sleep enables your brain to repair itself
Make some predictions – If this is true
then……………….
Predictions of Oswald’s theory
1. Sleep deprivation will lead to a deficit in
functioning
2. You get a ‘rebound’ following deprivation
3. There is an increase in REM during brain growth,
reorganisation & repair
4. There is an increase in SWS during illness,
recovery from injury
Sleep deprivation will lead to a deficit
in functioning
 If sleep (SWS& REM) is restorative, total sleep deprivation
should have negative effects…..
 Animal Studies
Rechtchaffen kept rats on a turning disc they died after 33
days
 The effects of total sleep deprivation
Case studies e.g. Peter Tripp stayed awake for 201 hours and
after 5 days experienced hallucinations and paranoia.
However…..
Microsleep (Williams et al)
BUT Randy Gardner found no Psychotic symptoms after 11
days without sleep.
Dement (1960) Effects of REM
deprivation were severe and
included increased aggression and
poor concentration.
Deficits when sleep
deprived?
Randy Gardner, a 17 year old student,
stayed awake for 11 days (260) in
1965 and effects included
disorganised speech, blurred
vision, and a small degree of
paranoia.
DJ Peter Tripp - 1959
Stayed awake for 201
hrs in a ‘wakeathon’.
After 3 days abusive,
5 days began to
hallucinate (spiders
in shoes).
Sleep deprivation will lead to a deficit
in functioning
Microsleep
• When participants, being monitored, have
been sleep deprived for over 72 hours they
had short periods of MICROSLEEP while
apparently awake.
• Williams et al 1959 - EEG recordings show
that microsleep is the same as sleep
The effects of sleep deprivation
AIDs
• Methodological issues………
• Case studies
• Issues with animal studies
• Ethical issues
You get a “rebound” following
deprivation
The effects of Partial sleep deprivation
Rebound effects (Empson 2002)
When people are deprived of SWS they show
the need for more SWS the next night
The same for REM sleep.
Rebound effects?
• Dement (1960)
• PPs deprived of REM sleep
seemed to have a need to
catch up Attempts to enter
REM sleep doubled from an
average of 12 to 26 times
by the seventh night.
• When allowed to sleep
normally the participants
spent much longer than
normal in REM sleep, as did
Randy Gardner.
Rebound
• Generally, people catch up on sleep following
deprivation
– Not all lost sleep is reclaimed
– About 70% of lost SWS and about 50% of lost REM
typically recovered
–Only some sleep is necessary
–‘Rebound’ suggests that sleep is a
necessary function
Increase in REM sleep during brain
growth, reorganisation and repair?
Growth & reorganisation
24 hour period
5yrs
REM
NREM
Age
• Reduction in
sleep over
lifespan
• Highest in
infants;
highest REM
in early years
• Some changes
in
adolescence
Evidence that REM sleep enables
brain recovery.
Brain Growth
More REM sleep in babies and even more in
premature babies
Suggests REM sleep may be important for brain
growth.
Siegel suggests the amount of REM in any
animal is related to how immature they are at
birth.
Evidence that SWS enables body
repair
Growth hormone is secreted during SWS
Important in childhood & for protein synthesis &
cell growth.
THIS IS VITAL IN THE RESTORATION OF BODY
TISSUE
What happens in old age?
Evidence that SWS enables body
repair
The immune system
Lack of SWS has also been associated with
reduced functioning of the immune system.
The immune system consists of various proteins
and anti bodies which are regenerated during
cell growth and protein synthesis in SWS.
Restoration theories
Oswald
(1966)
“Every stage of
sleep is essential
for restoration!”
A. SWS1-4 are all needed:
for repair/restoration of
the body
B. REM is essential: for
repair/restoration of the
brain
“No! Only
SWS4 and REM
are essential for
restoration!”
Horne
(1988)
1. ‘Core sleep’ = SWS4 + REM:
essential for repair/restoration
of the brain
2. ‘Optional sleep’ = SWS1-3:
not needed at all for
repair/restoration
Restoration of the body happens
when we are awake and relaxed
http://www.psychology4a.com/biological_rhythms.htm
Evaluation
The FACE VALIDITY of this theory is high – it makes
sense.
 It is easy to obtain quantitative (OBJECTIVE?) data
on REM, amount of neurotransmitters etc
X Extrapolating from hamsters, cats and rats to
humans is always risky.
X The research is not always RELIABLE and so we
might question its VALIDITY. ( human sleep
deprivation studies and animal sleep deprivation
studies – fatal or not fatal?)
X Case Studies
Jouvert 1967
Cats placed on islands of
flower pots floating in water.
They could balance on the
pot and enter stages 1-4
sleep but in REM muscles
would relax and cat would
fall into the water and wake
up. So REM deprived. The
cats became disturbed and
died after about 35 days
Shapiro et al 1981
Runners sleep patterns were studied
and found that those runners in a
marathon slept for an extra hour on 2
nights following a race. It was their SWS
which increased. Compared to non race
days sleep.
Horne 1988
Amino acids which form
proteins come from our
food. Therefore if amino
acids are to make protein
during SWS we would need
to go to bed within five
hours of eating as this is
how long they remain in the
body! We don’t usually
manage this though!
Newborn babies
spend up to 18
hours asleep
Neurotransmitters
restored
REM requires a lot of
neural activity of the brain.
How could this restore
neurotransmitters? Surly it
would in fact use them up!
Randy Gardener/
Peter Tripp
Restoration Theory of Sleep
I can outline the restoration theory of sleep
E
C
A
I can describe some studies and case studies
that support or undermine the restoration
theory
I can evaluate theories using AIDS
O + E One or more functions of Sleep (24)