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  • Sleep Topic
    • Biological rhythms
      • Circadian rhythms
        • Michel Siffre's cave study into exogenous pacemakers
          • Gender bias, individual differences, validity, deterministic
        • Sleep/wake cycle
        • Hormones
          • Melatonin induces sleep, cortisol causes alertness. cortisol is present during early morning. Melotonin is present during the night
        • Endogenous and exogenous zeitgeibers
      • Infradian rhythms
        • Monthly cycles such as the menstrual cycle
          • Russell et al - role of pheromones in controlling cycles. Putting sweat on the top lip of women. Periods synchronised
          • PMS - consequence of the menstrual cycle
        • SAD (seasonal effective disorder)
          • People tend to get sad during the winter months due to more melatonin, meaning less serotonin.
            • Real world application - treating SAD using UV light exposure during the winter months to promote serotonin levels.
      • Ultradian  rhythms
        • cycles that last less than a day - sleep stages
          • Stage 1, 2, 3,4 and REM
            • stage 3 and 4 are SWS (slow wave sleep), associated with growth hormone and restoring cells etc happens
            • Dement et al: not all REM sleep is dream sleep. When waking participants in REM sleep, not all reported dreaming. This makes it harder for psychologists to identify what causes dreaming.
          • Basic rest activity cycle
            • Freidman and Fisher detected a clear 90 minute cycle in eating and drinking behaviour
    • Disruption of biological rhythms
      • Shift work
        • Decreased alertness, sleep deprivation and health effects
          • Boivin found that night workers experience a circadian trough of decreased alertness during their shift, occurring when cortisol and temperature was lowest
          • workers who have to sleep by day have sleep problems as there are noises that keep them awake. Poor sleep makes it more difficult for the workers to stay awake
          • Knutsson found that individuals who worked shifts for more than 15 years are three times more likely to develop heart disease
        • shift work effects can be due to other factors too. Lack of sleep due to having to go to bed at unusual times
        • rotating shifts has been found to be more disruptive than non-rotating shifts as the person cannot settle into a rhythm
        • Melotonin has been found to be a 'miracle cure' for shift work and jet lag, as it induces sleep. Petrie (2001) found that melotonin taken near bed time is very effective
      • Jet lag
        • Jet lag is used to describe what happens to the circadian rhythm when exposed to extreme changes
          • There may be other factors that effect jet lag, for example, not getting enough sleep the night before due to worrying about travel.
        • Recht et al looked at major league baseball teams to see how jet lag affected their performance.those that travelled from west to east won 37% of games, and those travelling east to west won 44% of games. Those travelling from east to west experienced phase delay.
        • Real world application - using artificial lighting to restore the circadian rhtyhm
    • sleep and life-span changes
      • Infancy - babies sleep more than children and adults, around 16 hours non-continuous sleep. They experience immature versions of SWS and REM sleep, and do not fall straight into deep sleep, they have a period of light sleep beforehand then gradually fall into a deeper sleep
        • babies sleep patterns may be an adaptive response to llow parents to get on with chores during the day. REM can be accounted for due to the amount of learning that is taking place.
      • Childhood - Chldren have more REM sleep and sleep for around 12 hours a day with more adult looking EEG patterns.
      • Adolescence - circadian rhythms change leaving teenagers more awake at night time with sleep being round 9-10 hours a night
        • changes in sleep may be linked to hormonal changes, hormones are released at night, possibly causing the sleep deprivation.
      • Adulthood and old age - older people tend to have difficulty falling asleep and wake up more frequently. REM sleep decreases to around 20% of total sleep time and SWS reduces to as little as 5%. Older people sleep earlier and wake earlier
        • problems staying asleep can be due to the fact that SWS is reduced, so the older sleeper is more easily awoken by noise etc. Sleep deficit in old ge may explain why they suffer from decreased alertness. Sleep apnoea can also be the cause of reduced sleep.
    • Functions of sleep
      • Restoration explanation
        • Slow Wave Sleep (SWS) - growth hormone is secreted during SWS, stimulating growth. Important in childhood. Important in adulthood as it allows protein synthesis to happen and cell restoration.
        • Sassin et al found that when the sleep wake cycles are reversed by 12 hours, so is the production of GH. This shows that GH release is controlled by neural mechanisms in SWS.
        • REM sleep  - REM sleep allows for a break in neurotransmitter release which allows neurones to regain sensitivity. REM sleep may be important in memory, such as remembering how to ride a bike, but SWS is for semantic memory such as knowledge.
        • Non human studies show that the effects of sleep deprivation can be fatal. Rechtschaffen forced rats to stay awake by rotating a disc they were standing on every time they went to sleep, after 33 days all rats died. No sleep means death
        • Untitled


Rhianna Sly


Not finished yet, but close. 

Farhan Munim


This is great! So far we've covered 2 of the 3 sub-sections, I was wondering if this is completed?

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