Endogenous Pacemakers and Exogenous Zeitgebers
Intro: Biological rhythms from inside us- endogenous pacemakers, outside control- exogenous zeitgebers. Circadian: Endogenous factor- SCN- light enters through eyes and optic nerve fibres track to the SCN, this stimulates the pineal gland to reduce melatonin levels (high melatonin=sleepy). Stephan and Zucker found that damaging the SCN of rats would disrupt thier circadian rhythms including SWC. Without the zeitgeber of light, the body is still capable of regulating rhythms. Michel Siffre- spent over 6 months in a cave, found his SWC to be 25 hours. However, case study (only one p), other factors could have affected behaviour eg loneliness, Groblewski found similar findings with rats, lasted a long time. Miles- blind man had SWC of 24.9 hours, Luce and Segal- people who live in Arctic Circle still sleep for 7 hours. SAD (seasonal affective disorder)
Infradian: Female menstual cycle. Average cycle 29.5 days, endogenous rhythm affected by exogenous factors. Reinberg spent 3 days in dimly lit cave, menstrual cycle became 26 days and took year to return to normal. McClintock found women who spend a lot of time together become synchonised (pheromones). Supported by Russel- 4 out of 5 women became synchronised with donor after rubbing pheromones on lips for 5 months.
Distruptions- Jet lag: affects SWC, digestion, hormones. Klein- adjustment of westbound flights much quicker due to ability to wait rather than catch up. Shift work: odd shifts disrupt body clock and cyles, also can cause depression and physical illness (Sack et al).
Theories of Sleep
Intro: Restoration and Evolutionary theories
Restoration: Repair and recharge the brain and body. Oswald- NREM = body, REM = brain. Krueger et al- lack of SWS = reduced functioning of immune system (shift work). Stern and Morgane- REM replenishes neurotransmitters. We sleep more during times of stress and illness. Total sleep deprivation- Peter Tripp (8 days, hallucinations), Randy Gardener (11 days, disorganised speech, blurred vision, paranoia) both unrepresentative. Rechtschaffen et al- prevented rats from sleeping, all died within 33 days. Fatal familial insomnia, people stop sleeping at middle age and die within 2 years. Problems with self reports.
Evolutionary: Predator avoidance, supported by Meddis (sleep wastes time). Webb said it to conserve energy, however Capellini found that larger animals sleep more (conservation would be needed for small animals with high metabolic rate). Genetically close species have similar sleeping patterns, suggesting it is evolutionary.
Conclusion: Horne suggested core sleep (SWS) and optional sleep (REM). Core repairs and optional is to occupy unproductive hours for conservation and avoidance.
Disorders of Sleep
Intro: Parasomnia (insomnia, narcolepsy, sleep walking).
Insomnia: Age (Roberts- teenage insomnia. 25% experienced insomnia, year later, 41% still had it), gender (females + hormones), personality (Kales et al- internalising psychological disturbances). Diathesis stress model would suggest something must trigger it such as relationship/work problems. Epsie- when original cause is gone, insomnia can carry on due to anticipation of not sleeping. Chronic insomnia highly complex and not likely to be due to a single factor. Meaningful research difficult and hard to draw firm conclusions.
Narcolepsy: Each attack triggered by emotional arousal, affects one in 2000. Explanations- REM- Vogel (1960)- some evidence for REM activity during sleep attacks, Siegel- narcoleptic dogs showed signs of REM activity during cataplexy. HLA- Honda et al (80s)- narcoleptic patients had more HLA, however Mignot et al found it was not common in all narcoleptics and was common in general population. Hypocretin- neurotransmitter maintains wakefulness. Lin et al- gene mutation in dogs which disrupted production. Nishino- human narcoleptics had lower levels of hypocretin. Mignot- not genetic and could be due to brain injury, infection, poor diet or auto-immune attack.
The Nature of Dreams
Intro: Neurobiological theory and psychological theory.
Neurological: Hobson and McCarley, Activation Synthesis- dreaming is due to high levels of activation in areas of the brain resposible for perception, action and emotion during REM. Activation is signals generated in the brain. We interpret these as if caused by external stimuli. Hobson suggested our quest for meaning makes it coherant. Hobson found cats had random firing of cells during REM, however dreaming isn't exclusive to REM. Doesn't explain why some dreams relate to current problems etc. Strong scientific support, but doesn't take into account free will (lucid dreaming).
Psychological: Freud's Wish Fulfilment theory- wish fulfilment for repressed desires. Unacceptable thoughts repressed into unconscious which come out in dreams. Symbolisation within manifest content gives insight into latent. Freud used his own dreams and his patients as evidence for this theory. People giving up smoking often dream about smoking for months afterwards showing wish fulfilment. 60%+ of dreams involve negative emotions, contradicting wish fulfilment. Not all dreams are about sex. Era dependant, however we can imagine there was much repression at this time. Not falsifiable, and only 5% remembered therefore not representative of other 95%.
Conclusion: Most likely to be closer to Neurological theory due to advances in psychological knowledge, newer.
Intro: Not like sleep, EEGs resemble that of wakefulnes. McIlveen- prone to fantasy=willling to follow orders. State and non state theories.
State: Hilgard- neodissociation theory- separation of one part of the body from the rest. Cold pressor test- part of the brain which registers pain is separated from that of basic responses. Hidden observer- part of conscious is still aware of whats going on and can go back to this. Hilgard also put forward induced deafness.
Non state: Social influence- compliance and demand characteristics, Asch and Milgram. Barber- all hypnotic phenomena can be replicated by the non hypnotised. McIlveen - hypnotised person believes they are hypnotised whereas the imitator does not. No measure of brain activity has distiguished between the two (Sarbin and Slagle).
Conclusion: A lot of hypnotic phenomena can be explained by non state, however the role of hypnotic analgesia gives evidence for state theories as it would be difficult to withstand that kind of pain.