Sleep Biological Psychology - OCR Level 5 PDF

Sleep BIOLOGICAL PSYCHOLOGY - LEVEL 5 DR LYNNE MARROW Introductio n In this lecture we will look at: The stages of sleep Some theories of sleep What happens in sleep deprivation The function of sleep Introduction Questions: How much sleep do you think you need? How much sleep do you get?...

Sleep BIOLOGICAL PSYCHOLOGY - LEVEL 5 DR LYNNE MARROW Introductio n In this lecture we will look at: The stages of sleep Some theories of sleep What happens in sleep deprivation The function of sleep Introduction Questions: How much sleep do you think you need? How much sleep do you get? Does it make a difference if you don’t get the sleep you need? Do we need more or less sleep as we get older? Why do we sleep? Introduction We spend about one-third of our lives asleep. Most adults require 7-8 hours of sleep, although this varies between individuals. Infants, require about 16 hours a day, teenagers need about 9 hours of sleep. As people age, they tend to sleep more lightly and for shorter times. Why do we sleep? Evolutionary theories/ene Brain Recuperatio rgy processing n theories conservatio theories n Slightly Recover from Sleep to stay different the exertions safe at night than of the day recuperation. Brain Conserve processing energy and memory consolidation Sleep also helps creativity. Measuring Brain Activity Measuring Brain Activity Hans Berger, 1928 Discovered that by placing electrodes on a human scalp and amplifying the signal, he could display the underlying electrical activity. These are interpreted as waves of different frequencies These waves were state dependent  Recording Sleep Records electrical Electro- activity of the brain encephalog through electrodes ram (EEG): attached to the scalp Electromyo Electrodes attached to gram the chin measure (EMG): muscle activity. Electrodes attached Electro- around the eye oculogram measure eye (EOG): movements. Stages of Sleep Stages Of Sleep: Sleep cycles Stage 1 – falling asleep Stage 2 – sleep becomes deeper Stage 3 – delta waves and deep sleep Stage 2 New stage of sleep Stages Of Sleep: A new stage… Michel Jouvet (1950s) Studying cats – noticed that when asleep, for periods there were high levels of brain activity Paradoxical sleep Kleitman and Aserinsky (1955) Measuring depth of sleep by monitoring eye movements Found periods of rapid eye movement Rapid Eye Movement (REM) sleep Stages Of Sleep: REM Sleep REM sleep is similar to stage 1 non-REM sleep, however: The brain is active during REM sleep – looks most like wakefulness. The EOG shows that the eyes are darting around, beneath the eyelids. The EMG shows that muscle movement has decreased considerably – muscle atonia. Stages Of Sleep: REM Sleep REM Kleitman (1957) 80% of people woken from REM sleep sleep: recall a dream 7% of people woken from nREM sleep associat recall a dream Solms (1997) ed with Some brain damaged people continue to have REM sleep, but do not report any dreamin dreams Others report dreams, but do not appear g to express REM sleep Sleep Deprivation Sleep Deprivation Sleep deprivation schedules range from slightly reduced amounts of sleep during one night, to total sleep deprivation for several nights 3 consistent effects after even moderate sleep deprivation: 1. Increased sleepiness 2. Disturbances on written tests of mood 3. Perform poorly on tests of vigilance Sleep Deprivation – Vigilance Dinges et al (1997) 2 or 3 days of continuous sleep deprivation causes microsleeps Brief periods of sleep (2 or 3 secs long) Subjects become less responsive to external stimuli Affect performance on tests of vigilance, but not necessary for these deficits to occur Sleep Deprivation – Physical performance Van Helder and Radomski (1989) Reviewing the literature on sleep deprivation and physical performance, they found that 30-72 hrs sleep deprivation. No effect on: Cardiovascular and respiratory responses to exercise of varying intensity Physical strength Motor performance However, time to exhaustion was reduced by sleep deprivation Sleep Deprivation – Cognitive function Percival et al (1983): Tests of Mostly immune to disruption by sleep deprivation cognitive ability – IQ tests Horne (1983): Disrupted performance on tests designed to Tests of measure creativity creativity Nilsson et al Only some aspects of cognitive function are susceptible to sleep deprivation – those (2005): involving EXECUTIVE FUNCTION Complex These include innovative thinking, lateral executive tasks thinking, insightful thinking, planning etc. Selective Sleep Deprivation - REM Sleep Deprivation Dement (1960) - Deprived participants of REM sleep As deprivation progressed, subjects had Found: to be woken more frequently from REM sleep When permitted to sleep normally after Furthermor a period of deprivation, participants spent a greater than normal percentage e: of the night in REM sleep Suggests a need for REM sleep Role Of REM Sleep Bloch et Experience of training on a al task is related to amount of REM sleep required (1977) Smith Animals deprived of REM sleep after training on a task, (1996) learn the task more slowly Suggest a role in the facilitation of learning Selective Sleep Deprivation - SWS Role Of Slow Wave Sleep Sakai et al (1979) During slow wave sleep, cerebral metabolic rate and cerebral blood flow decline During stage 4 sleep, they are about 75% of waking level Regions with highest levels of activity during waking have highest levels of delta waves during SWS Role Of Slow Wave Sleep Horne and Minard (1985) Aim: to increase mental activity without affecting physical activity or causing stress Participants felt significantly more sleepy at bedtime Participants fell asleep more quickly Participants did not sleep more Participants showed an increase in SWS REM sleep was unaffected  Role Of Slow Wave Sleep HOWEVER recent work has revealed the importance of slow-wave sleep (SWS) for memory consolidation. Backhaus J, Junghanns K, Born J, et al. (2006) Studied a natural form of SWS deprivation - insomnia Patients with insomnia have reduced amounts of SWS, and this has been significantly correlated with reduced Backhaus (episodic) J,memory Born J,consolidation Hoeckesfeld R, et al. (2007) Increasing age (> 30 years old) is associated with diminished levels of SWS, which is associated with a decline in sleep-related memory consolidation. Conclusion Sleep occurs in all mammals, and probably all vertebrates. Humans can last a long time without sleep, but we crave sleep when deprived of it. Stages of sleep can be measured in the laboratory. The different stages of sleep may have different functions.  Further Reading JPJ Pinel, Biopsychology 7th edition. Chapter 14. Especially 14.1, 14.2, 14.3, 14.4, 14.6 and for those who are interested 14.7 Carlson, N.R. Foundations of Physiological Psychology. Chapter 8. Seigel, J.M (2003) Why we sleep. Scientific American Nov 92-97 Seigel, J.M. (2005) Clues to the functions of mammalian sleep. Nature 437:1264-1271 Articles can be found on Blackboard