Stress

Home AS A2 Links
Circadian Rhythm
Infradian Rhythm
Ultradian Rhythm
Jet lag
Shift Work
Evolutionary Theory of Sleep
Restoration Theory of Sleep
Sleep Deprivation Studies
Lifespan Changes in Sleep
Insomnia and OSA
Narcolepsy and Somnambulism
10% on sleeping tablets

 

 

 

 

Sleep deprivation studies

These are interesting in their own right, but from a practical point of view can be used:

·         As evidence for the restoration theory of sleep

·         In an essay on the methods used in the study of sleep

·         As an example of disruption of biological rhythms

 

Total sleep deprivation

Humans

These studies tend to be carried out on student participants at various universities, for example Loughborough and Edinburgh in the UK.  There are also the two infamous cases of sleep deprivation for the purposes of charity and notoriety in the Guinness book of records.

Case studies

Peter Tripp spent 201 hours and 10 minutes awake, much of it sitting in a glass booth in Times Square, spinning records and bantering into his microphone three hours a day.

When Mr. Tripp began to fall asleep, nurses shook him; doctors joked with him, played games with him and gave him tests to take. After a few days, he began to hallucinate, seeing cobwebs, mice, kittens; looking through drawers for money that wasn't there; insisting that a technician had dropped a hot electrode into his shoe.

His last 66 hours awake were spent under the influence of drugs administered by the doctors and scientists observing him. Asked at the end of his stunt what he wanted the most, Mr. Tripp said, not surprisingly, that he wanted to sleep, which he then did for 13 hours and 13 minutes.

Mr. Tripp's career was indelibly tarnished by the 1960 payola scandal, in which he and several other disc jockeys and radio station employees were indicted on charges of accepting money from record companies in exchange for playing their records.  Tripp later blamed his involvement, at least in part, to his sleep deprivation.

Peter Tripp during his wakeathon attempt

Randy Gardner (1965) stayed awake for a record breaking 11 nights as part of a school science project!!!.  He reported blurred vision, slurred speech, mild paranoia in which he began to believe that the researchers watching him thought he was stupid.  When Randy was allowed to sleep he did so for 14 hours and 40 minutes on the first night and two hours longer than usual on the next two nights.  So, despite losing about 90 hours sleep he only made up about 11.  However, he did catch up on a disproportionate amount of his lost stage 4 (68%) and REM sleep (53%) suggesting that these are the vital stages.  There were estimated to be 67 hours of sleep that he did not make up. Despite his exploits he suffered no long term consequences.

 

Note:

In fact Randy never made it into the Guinness Book of Records because, according to Wiki, a month later Toimi Soini of Finland beat the record by a few hours.  (Why so little about this effort is known I’m not sure).  In 1989 the record was removed from the book because of fears that it would encourage others to risk their health by attempting to beat it. Earlier this year, Tony Wright of Penzance stayed awake longer than Gardner but unaware of Toimi Soini’s record fell just short of the last Guinness World Record 

Accounts of the degree to which Gardner suffered during the attempt vary.  The official report by Dement paints a picture of little or no cognitive disfunction.  On the tenth day of his ordeal Dement interviewed Gardner and then took him for a game of pinball, which Gardner won.  However, John J. Ross a commander of the U.S. Navy Medical Neuropsychiatric Research Unit in San Diego, who was called in by Gardner’s parents, describes a more serious loss of ability. 

In the first few days these included problems focusing, inability to repeat simple tongue twisters and moodiness.  By day four there was memory loss and the first hallucination, he imagined that a street light was a person.  Later in the same day he had a delusional episode, imagining himself to be a famous black footballer!

By the end of the first week speech had slowed and become slurred and he was having problems…. *

By the last two days his loss of cognitive ability was far more marked than Dement suggests.  When asked to count backwards from 100 in evens he stopped at 65.  When asked why he said he couldn’t remember what he was supposed to be doing.  He became paranoid and his speech was slow and without intonation.

*finishing sentences!

Evaluation

It is difficult to generalise to the general population with case studies like this that by definition have a very small sample size, particularly with such different findings between studies.   Most research since has backed this up.  Greatest impairment appears to be in boring tasks and those requiring close attention.  Sleep deprived radar operators in the war would miss enemy planes appearing on the screen.  Tired car and lorry drivers may have accidents following a few seconds of micro sleep in which consciousness fades and the eyes de-focus. 

In cases of fatal familial insomnia, people sleep normally until middle age when they suddenly stop.  Death is usually within two years!  Lugaressi et al (1986) reported the case of a man with brain damage who as a result slept very little.  He was unable to live a normal life and eventually died as a result!

 

 

Larger studies on human participants

The main study is the meta-analysis carried out by Huber-Wiedman who collated the data from a large number of sleep deprivation studies.  The findings are summarised in the table:

Nights without

Symptoms

1

Discomfort

2

Urge to sleep especially between 2 and 4 in the morning

3

Cognitive tasks requiring concentration are seriously impaired, especially if they are repetitive or boring.

4

Periods of micro sleep are unavoidable and the volunteer becomes irritable and confused.  The ‘hat phenomenon’ occurs.

5

Still irritable and confused and may also become delusional.

6

Person becomes depersonalised with a loss of self identity.  This is referred to as ‘sleep deprivation psychosis.’

Webb & Bonnett (1978) used a different method of sleep deprivation.  They got their participants to gradually reduce their sleep by 2 hours.  Participants reported no ill effects.  In a follow up they got them to reduce sleep to only 4 hours per night, again without problems.

Evaluation

Even with larger sample sizes such as this study there are still serious issues with the methodology.  The participants are under tightly controlled conditions and know that they’re being watch 24 hours a day.  This will involve massive demand characteristics and presumably with people that have volunteered to remain awake for long periods they will probably view it as a competition.  This will not only create a level of stress but also significantly increase motivation. 

Additionally, Dement himself admits that his own observations of participants are a big source of bias due to his own expectations when observing volunteers. 

 

Overall evaluation of human deprivation studies

On the face of it they do appear to support the restoration theory.  However, with some of the studies it could be stress resulting from deprivation rather than deprivation per se that caused the effects observed.  Hence we have problems with cause and effect

Dement’s work was carried out in sleep laboratories and this in itself may have caused disruption to the night’s sleep.   In the case of Webb & Bonnet there is also the issue of social desirability bias with participants just wanting to look psychologically tough.

The concept of total sleep deprivation is very artificial.  It is exceptionally rare for people in real life to go completely without sleep for any length of time.  As a result the studies lack ecological validity, more so than studies of partial deprivation.  Betty Schwartz in the USA studies cases of supposed total insomnia, in which patients claim that they never sleep.  However, when tested under lab conditions it is usually found that they have quite a good nights sleep, but without realising it.

One finding that does appear common to animal studies and human case studies is that total sleep deprivation is fatal and as yet we don’t understand why!

·         In the human studies participants are aware that they are being observed and this may well affect their behaviour.  Bentley (2000) says that Dement recognised this as being an issue in his 1960 study. 

Animal studies (total sleep deprivation)

Rechtschaffen et al (1983) placed rats on a disc over water.  Each time that its EEG suggested it was falling asleep the disc would rotate forcing the rat to walk to stay out of the water.  A second rat was used as a control.  This had to do the same amount of walking but was able to sleep when the other rat was awake.  The experimental rats started to lose weight after a week due to increased metabolic rate started to eat more.  Despite this, the weight loss continued and after about three weeks the rats started to die.  After 33 days all the sleep deprived rats were dead.

Partial sleep deprivation

In these procedures volunteers are deprived of part of their night’s sleep, i.e. deprived of REM or deprived of NREM sleep only.

Humans

Dement (1960) deprived volunteers of either REM or NREM sleep and observed the consequences.  He found that REM deprivation was most dramatic with participants becoming more aggressive and having very poor concentration.  He also reported REM rebound effects, in which participants would try and catch up on lost REM sleep.  For example going straight into REM when allowed to go back to sleep.  By the seventh night Dement reported that participants were averaging 26 attempts per night to enter REM.  After the procedure when they were allowed an uninterrupted nights sleep they spent much longer in REM.  This is similar to the results reported following the Randy Gardner study and again reinforces the apparent importance of REM sleep.

In practice partial sleep deprivation is not possible over any period of time since participants need to be woken so often it quickly deteriorates into total sleep deprivation.

 

Animals

Jouvet (1967) used the flower pot technique to deprive cats of REM sleep.  They would be placed on an upturned flower pot in a tank of water. This allowed them to sleep, but when they entered REM and lost muscle tone they would fall into the water. They then climb back onto the flowerpot renter the stages and fall back in once REM is reached.  In fact after a number of trials the cats become conditioned.  On reaching REM they wake up before falling into the water on many of the trials.  The study again is very unethical and cruel.   On average the cats survive for 35 days.

 I couldn’t find a picture of Jouvet’s cats on a flowerpot, however, this is a rat on a flowerpot in a bowl of water. 

Overall evaluation of animal deprivation studies

·         With animal studies there are clearly issues of generalising to humans. 

·         The animal studies are particularly cruel since unlike humans the animals have no idea that the experiment will eventually end!

Conclusions on sleep function (courtesy of Dwyer and Charles).

The evolutionary theories of sleep are unable to explain why sleep deprivation has such adverse effects whereas theory restoration can.  However, it is clear that sleep is essential for survival and this is in agreement with the evolutionary theory’s adaptive value of sleep.  Modern ideas assume that restoration does in itself serve an adaptive function so both evolutionary and restoration theories may be relevant.  Furthermore, sleep may serve other useful purposes as yet not considered.  One of these could be to allow us to dream.   As Shakespeare put it;  “to sleep perchance to dream.”
 

Next page