Restoration Theory

‘Our planet is a dangerous place, there is ruthless competition for limited resources and only the fittest survive. Yet all the most advanced animals, normally alert, shrewd and watchful, drop their defences to sleep’ (Blakemore, 1988).

Sleep occupies 1/3 of our time. What we are interested in when we study sleep:

What function is served by sleep?What happens when we are deprived of sleep?Why do most animals sleep?

In order to understand the functions of sleep, researchers

have looked at the effects of sleep deprivation...

Jouvet (1967)

• Aim: To examine the effects of REM sleep deprivation on a domestic cat

• Method: The cat was placed on a small island surrounded by cold water

Whenever the cat feel asleep, it would fall into the water and instantly wake upThis was continued for 75 days

• Results: The cat became progressively more disturbed and eventually died

Rechtschaffen et al. (1983)

Aim: to examine the effects of sleep deprivation on rats

Method: Rats were forced to remain physically active by rotating a disc every time they started to go to sleep

Results: After 33 days, the rats had all died

Dement (1960) Effects of REM deprivation were severe and included increased aggression and poor concentration.

Deficits when sleep deprived?

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.

Example : (Horne 1988) Randy Gardner remained awake for 264 hrs/ 11 days in 1964. Toward the end of the 11 days he suffered from slurred speech blurred vision and paranoia. He had less symptoms that Peter Tripp (page 13, book) but was awake an extra 3

days.

After his deprivation Randy slept for 15 hours he slept for longer than usual for a few nights after but soon reverted back to his usual sleep pattern. He only recovered about 25% of the

sleep lost (80-90hrs)

If sleep were that essential, would you expect him to have recovered more?

Extensions for Learning...

Further studies using humans:

Webb and Bonnet (1979a and b)

Dement (1965)

The Restoration Theory Of Sleep

The function of sleep is to allow the body to be

repaired/ restored

SWS enables body repair. REM

sleep enables brain recovery(Oswald, 1980)

SWS EXPLANATIONS

• Growth Hormone

GH stimulates growth in children and protein synthesis in adulthood

A significant amount is released during SWS. Sassin et al. (1969)

The decline of GH in older age is associated with the reduction of SWS (van Cauter et al., 2000)

• Immune System: Lack of SWS has been associated with reduced functioning of Immune system (Kreuger et al., 1985)

Total sleep time increases during illnessREM increases during recovery from brain

injury, ECT & drug withdrawal

REM Sleep Explanations• Brain Growth: Active/REM sleep is higher in

babies and premature babies

Is the amount of REM sleep dependent on brain maturity at birth?

Siegel (2003):The platypus has about

8 hrs of sleep (Immature at birth)

Whereas dolphins haveno REM sleep and can

swim from birth

Explanations REM sleep • NeurotransmittersREM sleep allows for a break in neurotransmitter release permitting neurons to regain their sensitivity (Siegel and Rogawski, 1988)

• MemoryCrick and Mitchison (1983) proposed that during REM sleep unwanted memories are discardedStickgold (2005): REM sleep important for procedural memory consolidation. SWS for semantic

Evaluation

Extrapolating from hamsters, cats and rats to humans is always risky.The research is not always RELIABLE and so we might question its VALIDITY. (cf human sleep deprivation studies and animal sleep depriavation studies – fatal or not fatal?)Case Studies- 'Alien Among Us' criticismIt is easy to obtain quantitative (OBJECTIVE?) data on REM, amount of neurotransmitters etc

The main predictions of Restoration Theory are:

Deficits in functioning when sleep deprived

'Rebound' effects following sleep deprivation

Increase in REM sleep during brain growth, reorganiation and repair

Increase in SWS during times of illness or injury

The main problem......is the lack of death among humans who are sleep deprived!!

Task!

In pairs. One person is a radio presenter, the other, a sleep specialist.

In your pairs, practice asking and answering questions as if on a radio show.

Extension for Learning!

Oswald (1980) and Horne (1988) are central to the restoration theory

Using the internet, discover how their approaches differ slightly.

c.400-500 words

Due Date: Wed 24th Nov