OxfordAQA International A-level Psychology (9685): 3.3.1 Psychology of sleep – Revision Notes

These notes condense the Psychology of sleep study guide. Read that first if anything here is new.

They follow section 3.3.1 of the OxfordAQA International AS and A-level Psychology (9685) specification, Version 3.1 (International A-level exams May/June 2020 onwards). The specification places Psychology of sleep in Section A of Unit 3: Advanced topics and research methods 2, a 1 hour 30 minute written exam worth 90 marks and 30% of the International A-level. Section A is worth 30 marks and its questions are compulsory.

Practise with the sleep practice questions. See the 9685 course hub, the 9685 checklist and the Unit 2 biopsychology revision notes for the nervous and endocrine systems.

What the specification lists

1. Biological rhythms: circadian, infradian and ultradian; endogenous pacemakers and exogenous zeitgebers and the sleep/wake cycle.
2. Disruption of biological rhythms: shift work and jet lag.
3. The nature of sleep: types of sleep, non-REM and REM.
4. Functions of sleep: evolutionary explanations; restoration theory; memory consolidation.
5. Sleep disorders: insomnia, including personality factors and genetics; narcolepsy.

The assessment objectives are AO1 (knowledge), AO2 (application) and AO3 (analysis and evaluation). The specification gives Unit 3 approximate weightings of 9% AO1, 10% AO2 and 11% AO3 of the full A-level, so evaluation and application matter as much as description. Research methods and maths skills are also assessed in Unit 3.

Key terms

Term	Meaning
Circadian rhythm	A cycle of about 24 hours, e.g. sleep/wake, body temperature
Infradian rhythm	A cycle longer than 24 hours, e.g. menstrual cycle, seasonal affective disorder
Ultradian rhythm	A cycle shorter than 24 hours, e.g. the 90-minute sleep stage cycle
Endogenous pacemaker	Internal clock; mainly the suprachiasmatic nucleus (SCN) in the hypothalamus
Exogenous zeitgeber	External cue that resets the clock; mainly light, also meals and social routines
Entrainment	Bringing the internal clock into line with external cues
Free-running rhythm	A rhythm that continues with no zeitgebers; in humans, slightly over 24 hours
Melatonin	Hormone released by the pineal gland in darkness; promotes sleep
Desynchronisation	Internal rhythms out of step with each other or with the outside world
Phase advance / delay	Moving the clock earlier (harder) / later (easier)
Slow-wave sleep (SWS)	NREM stages 3 and 4; delta waves; deepest sleep
REM sleep	Rapid eye movements, waking-like EEG, muscle paralysis, vivid dreams
Core sleep	Horne’s term for the SWS and REM needed for normal function
Hyperarousal	Raised physical and mental arousal that blocks sleep
Cataplexy	Sudden loss of muscle tone, often after strong emotion; a feature of narcolepsy
Hypocretin (orexin)	Hypothalamic neurotransmitter that stabilises wakefulness; reduced in narcolepsy with cataplexy

Studies at a glance

Who	What	Finding	One evaluation point
Siffre (1962)	About two months alone in a cave	Sleep/wake cycle continued but ran slightly over 24 hours	Single case; cannot generalise alone
Aschoff and Wever	Volunteers in an underground bunker	Most free-ran a little over 24 hours	Artificial light may have reset the clock
Ralph et al. (1990)	SCN transplants in hamsters	Recipients took the donor’s 20-hour rhythm	Animal study; generalising to humans needs care
DeCoursey et al. (2000)	SCN damaged in chipmunks, returned to the wild	More killed by weasels than controls	Ethical concerns about harm to animals
Campbell and Murphy (1998)	Light on back of the knee	Rhythm shifted	Later work failed to replicate
Stern and McClintock (1998)	Armpit compounds applied to other women	Menstrual cycle length changed	Many other factors affect cycle length
Czeisler et al. (1982)	Rotas of rotating shift workers	Forward, slower rotation improved schedule satisfaction, health ratings and productivity	Real workplace, so high ecological validity
Recht et al. (1995)	Baseball results after travel	Teams flying east did worse than those flying west	Correlational; travel stress is a confound
Dement and Kleitman (1957)	Woke sleepers in REM and NREM	REM wakings usually produced dream reports	Relies on self-report
Zepelin and Rechtschaffen (1974)	Sleep across species	Smaller, faster-metabolism animals sleep more	Many species do not fit
Allison and Cicchetti (1976)	Sleep across 39 mammal species	Species in more danger from predators had less REM sleep	Correlational comparison
Shapiro et al. (1981)	Runners after a 92 km race	More SWS and total sleep afterwards	Supports body restoration
Randy Gardner (1964)	264 hours awake	Recovered a fraction of lost sleep, but more SWS and REM	Single case
Jenkins and Dallenbach (1924)	Recall after sleep vs waking	Better after sleep	May reflect less interference, not consolidation
Plihal and Born (1997)	Early vs late night sleep	SWS-rich helped facts; REM-rich helped a motor skill	Lab tasks may lack everyday validity
Rasch et al. (2007)	Odour cue during SWS	Improved later recall	Strong experimental control
Siegel (2001)	Review of REM and memory	REM-suppressing antidepressants without clear memory loss	Challenges a REM role
Lin et al. (1999)	Narcoleptic dogs	Mutation in a hypocretin receptor gene	Human narcolepsy is rarely single-gene

Must-know distinctions

• Circadian vs ultradian sleep rhythms. The sleep/wake cycle is circadian. The cycle of sleep stages within a night is ultradian.
• Pacemaker vs zeitgeber vs hormone. The SCN is the pacemaker, light is the zeitgeber, and melatonin is the hormone that carries the signal.
• Phase advance vs phase delay. East travel and backward shift rotation need an advance (harder). West travel and forward rotation need a delay (easier).
• SWS vs REM. SWS is deep, with delta waves and body restoration. REM has waking-like EEG, a paralysed body and vivid dreams.
• Evolutionary vs restoration. Evolutionary accounts explain why sleep evolved (safety, saving energy). Restoration explains what sleep does for the body and brain.
• Primary vs secondary insomnia. Secondary has another cause, such as pain. Primary has no clear separate cause.
• Personality vs genetics. Personality factors (neuroticism, worry) act through hyperarousal. Genetic factors are many small-effect variants, shown by family, twin and genome-wide studies.

Mini essay plan

Question type: “Discuss restoration theory as an explanation of the function of sleep.” Your teacher will confirm the mark tariff.

1. AO1: Oswald: SWS restores the body (growth hormone, tissue repair); REM restores the brain. Horne: core and optional sleep.
2. AO2 (if a scenario is given): use its details, for example an athlete’s longer, deeper sleep after a race.
3. AO3 support: Shapiro et al. (1981), more SWS after an ultramarathon; Randy Gardner recovered more SWS and REM than lighter sleep.
4. AO3 limitations: repair also happens while awake; exercise does not always increase sleep; Gardner was a single case.
5. AO3 alternatives: evolutionary explanations (energy conservation, safety); memory consolidation evidence from Plihal and Born (1997).
6. Judgement: sleep probably serves several functions. Restoration fits SWS well but cannot explain all of sleep alone.

The same shape works for other extended questions on this unit. For shift work and jet lag, describe desynchronisation and the phase advance/delay difference, then judge the evidence from Czeisler et al. and Recht et al. For insomnia, give the personality and genetic factors, then weigh correlational evidence and shared family environments.

Quick self-test

1. Give one example of an infradian rhythm.
2. Where is the SCN?
3. Which gland releases melatonin, and when?
4. Why is a phase delay easier than a phase advance?
5. What did Ralph et al. (1990) transplant?
6. Which shift rotation did Czeisler et al. (1982) find better?
7. Name two EEG features of NREM stage 2.
8. Why is REM called paradoxical sleep?
9. What is Horne’s core sleep?
10. Which sleep stage did Plihal and Born link to declarative memory?
11. Name the three Ps in Spielman’s model.
12. Which neurotransmitter is lost in narcolepsy with cataplexy?

Answers

1. The menstrual cycle, or seasonal affective disorder.
2. In the hypothalamus.
3. The pineal gland, mainly in darkness.
4. The free-running rhythm is slightly over 24 hours, so staying up later suits the clock.
5. SCN tissue from mutant hamsters with 20-hour rhythms.
6. Forward rotation (days to evenings to nights), changing less often.
7. Sleep spindles and K-complexes.
8. The brain looks awake on the EEG but the body is almost paralysed.
9. SWS and some REM, which are needed for normal function.
10. Slow-wave sleep (early-night sleep).
11. Predisposing, precipitating and perpetuating.
12. Hypocretin (orexin).

Where marks are usually lost

• Calling the sleep/wake cycle ultradian.
• Naming light as the pacemaker and the SCN as the zeitgeber.
• Saying west-bound travel causes worse jet lag.
• Describing REM as deep sleep.
• Giving evaluation that could fit any study, such as “it lacks ecological validity”, without saying why.
• Using Siffre as if he were a large sample.
• Writing about insomnia without personality factors and genetics, which the specification names.
• Ignoring the scenario in application questions and writing a general definition instead.
• Treating correlational evidence, such as personality and insomnia, as proof of cause.
• Describing narcolepsy symptoms but giving no explanation.

Official syllabus

OxfordAQA International AS and A-level Psychology (9685) specification, Version 3.1 (International A-level exams May/June 2020 onwards), section 3.3.1 Psychology of sleep; Unit 3 details in section 2.3; assessment objectives and weightings in section 4.3.