PSYA3 - Sleep

The complete chapter on Sleep, for AQA "A" Psychology (A2)

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Biological Rhythms - Circadian and Ultradian Rhyth

CIRCADIAN RHYTHMS:

  • Once every 24 hours
  • SCN = internal body clock
  • Increased light = increased melatonin
  • Siffre - 61 days in cave. Sleep/wake cycle = 25hrs, but reached 48 hrs at one point
  • Folkard et al - 12 RP's in isolation. Clock was secretly changed. Only one person's rhythm adapted. 
  • Aschoff and Wever - WWII bunker. RP's had 25 hour cycle. 24 hour cycle when returned to normal. 

Ultradian Rhythms:

  • More than once every 24 hours. 
  • 5 stages of sleep (NREM, SWS, REM)
  • 90 minute cycle, 5- times per night. 
  • Friedman and Fisher - BRAC - Eating and drinking cycle. Study of psychiatric patients. 
  • Dement and Kleitman - REM studies are restricted. Assumption of dreaming sleep. Dreaming can happen in NREM, and not always in REM. 
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Biological Rhythms - Infradian Rhythms

Infradian Rhythms:

  • Less than once every 24 hours. 
  • e.g. Menstrual cycle/male monthly cycle
  • MENSTRUAL CYCLE: Pituitary glands release hormones which stimulate overy to ripen egg. Progestorone is released which causes increased blood flow. If no pregnancy, lining of womb is shed. 
  • MALE MONTHLY CYCLE: Empson - 21 RP's. study over 49-102 days. Body temp and alertness varied over 20 days. 
  • Russell et al - Sweat rubbed onto upper lip of another person. Menstrual cycles synchronised. 
  • Dalton - Premenstrual Syndrome (physiological problem, psychological symptoms) associated with crime, suicide, accidents. Can be defence in court. 
  • Seasonal Affective Disorder - Depression in winter. Melatonin and Serotonin released when dark. 
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Endogenous Pacemakers and Exogenous Zeitgebers

Endogenous Pacemakers:

  • Hypothalamus received information about light, even when eyes are closed. 
  • This synchronises the SCN, and sends signal to pineal gland to increase melatonin at night. 
  • Morgan - Mutant hamsters with sleep cycles of 20hrs. SCn transplanted into normal hamsters - They showed mutant rhythms. 
  • Folkard - Kate Aldcroft spent 25 days in a cave - sleep cycle was 30hrs. Temperature cycle was 24hrs. Therefore, desynchronsation has occured. 

Exogenous Zeitgebers:

  • Entrainment - resetting the SCN with Exogenous Zeitgebers, e.g. light, temp., social cues. 
  • DeCoursy et al - Destroyed SCN in chipmunks. They were more active at night, and were more likely to be killed. 
  • Campbell and Murphy - Shone bright lights onto back of RP's knees. Circadian rhythms shifted, therefore artificial light does have an effect. 
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Disruption of biological rhythms - Shift Work

Shift Work:

  • Decreased alertness - 00:00-04:00 = low cortisol levels and low body temp. This is a circadian trough. 
  • Sleep Deprivation - caused by distractions, light, noise, daytime sleep shorter than night. 
  • Effects on health - Knutson et al - shift work for more thatn 15 years = heart disease risk.
  • Solomon - Social disruption caused by shift work. Divorce rates are as high as 60%.
  • Gold et al - Rotating shifts are worse - constant changes and disruption cause stress. 
  • Bambra et al - Forward-rotating shifts are less damaging. 
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Disruption of biological rhythms - Jet Lag

Jet Lag:

  • Symptoms - Loss of apetite, insomnia, depression, fatigue, nausea, disorientation. 
  • Winter et al - SCN =1 day to adapt for every 1 hour of time change. 
  • Recht et al - Baseball teams from west and east America.                                                      -East to west = Phase delay (won 44%). West to east = Phase advance (won 37%).
  • Other factors - Bad sleep before travelling, travelling is tiring, noise, low-oxygen, noisy passengers
  • Boivin et al - 31 men, 4 groups. Sleep cycle inverted for 3 days. When awake, exposed to dim lighting and then either:
  • Group 1 - Very bright light. (Advanced 5hrs earlier)
  • Group 2 - Bright light. (Advanced 3hrs earlier)
  • Group 3 - Normal light. (Advanced 1hr earlier)
  • Group 4 - Dim light. (Advanced 1hr later)
  • Core body temp. was measured. 
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