Biological Rhythms

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  • Biological Rhythms
    • Biorhythms are the rhythms of living things, patterns of physiological processes repeated over time. Controlled by biological clock in the medulla.
      • Circannual: cycle of approx a year (also classified as infradian) eg migration, hibernation & SAD.
        • Gwinner: even when birds kept in a cage with no Ex Ze they still became more active in spring.
        • Pengelley & Fisher: kept squirrels in constant temp & light in lab over 1 yr. Found they still hibernated.
      • Ultradian: cycle occuring more than 24 hrs eg stages of sleep.
        • Sleep can be disrupted by alcohol.
        • Rosenwasser et al: found rats became more active just before feeding even without Ex Ze.
        • Ibuka & Kawamure: found if rats SCN removed rhythms disappear completely eg eating, sleeping drinking.
      • Infradian: cycle occuring less than 24 hrs eg human menstrual cycle.
        • Russel et al: found rubbing sweat from 1 woman on a group of others led to sync of cycles.
        • Reinberg: found menstruation cycle shortened when woman kept in cave for 3 months.
      • Circadian: cycle of 24 hrs eg sleep/wake cycle. Varies between individuals, cultures & age.
        • Ralph et al: bred hamsters to have 20hr cycle, transplanted their brains into normal hamster with 25 hr cycle, normal ones developed 20 hr cycle.
        • Luce et al: found people living near arctic circle (sun doesnt set in summer) still slept 7 hrs in 24 hr cycle.
          • Individual difference rarely occurs so findings of all studies are representative.
        • Siffre: spent 2 months in cave with no Ex Ze, developed 25 hr cycle instead of 24.
        • Miles et al: reported man blind from birth had rhythm of 25 hrs.
    • Controlled by
    • Disrupted by
      • Shift work
        • Is depended on by many industries. Shifts divided into slos & workers change from one shift to another every so many days.
          • Akerstedt: showed people on shift work sleep 1-4 hrs less, had a particular deficit in REM. Stated if REM had a specific function this would also show a deficit.
          • There are ways to reduce symptoms & therefore ways to avoid disasters.
            • Cziesler: reccomends a slow rotation of shifts (3 weeks before changing) so the body has time to adjust.
              • Bamber: contradicts. Says a fast rotation is better (3-4 days) as the body cannot get used to the shift.
            • Boivin et al: artifical light can help us adapt biorhythms to suit environment.
              • Supported by research into Ex Ze
            • Practical Applications: offers ways to improve health.
          • Conflict is caused when the body is working to one rhythm & the brain to another as these are usually in sync.
      • Jet lag
        • Is the tiredness & disorientation experienced by air travellers due to crossing time zones. Causes sudden inconsisteny between internal clock & outside cues.
          • Effects do not seem to happen when flights stay in the same time zone. Phase delay is easier than Phase advance.
            • Schwartz et al: studied results of baseball games. Found east coast teams travelling to play away games won more than west coast travelling to east.
              • Gender bias & culture bias. Validity issue,
          • Symptoms caused by melatonin release being out of sync with Ex Ze & inlcude fatigue, insomnia, anxiety, constipation/diarrhoea, dehydration & increased susceptability to illness.
            • Symptoms only temporary so not as bad as shift work.
          • Symptoms can be reduced in several ways.
            • Blakemore: recommends taking melatonin supplement pills in the evening to reduce effects.
            • Fuller: said food is good for altering biorhythms so suggests period of fasting before travel followed by only eating at times relevant to new time zone.
          • Individual Difference does occur: eg age.
  • Biorhythms are the rhythms of living things, patterns of physiological processes repeated over time. Controlled by biological clock in the medulla.
    • Circannual: cycle of approx a year (also classified as infradian) eg migration, hibernation & SAD.
      • Gwinner: even when birds kept in a cage with no Ex Ze they still became more active in spring.
      • Pengelley & Fisher: kept squirrels in constant temp & light in lab over 1 yr. Found they still hibernated.
    • Ultradian: cycle occuring more than 24 hrs eg stages of sleep.
      • Sleep can be disrupted by alcohol.
      • Rosenwasser et al: found rats became more active just before feeding even without Ex Ze.
      • Ibuka & Kawamure: found if rats SCN removed rhythms disappear completely eg eating, sleeping drinking.
    • Infradian: cycle occuring less than 24 hrs eg human menstrual cycle.
      • Russel et al: found rubbing sweat from 1 woman on a group of others led to sync of cycles.
      • Reinberg: found menstruation cycle shortened when woman kept in cave for 3 months.
    • Circadian: cycle of 24 hrs eg sleep/wake cycle. Varies between individuals, cultures & age.
      • Ralph et al: bred hamsters to have 20hr cycle, transplanted their brains into normal hamster with 25 hr cycle, normal ones developed 20 hr cycle.
      • Luce et al: found people living near arctic circle (sun doesnt set in summer) still slept 7 hrs in 24 hr cycle.
        • Individual difference rarely occurs so findings of all studies are representative.
      • Siffre: spent 2 months in cave with no Ex Ze, developed 25 hr cycle instead of 24.
      • Miles et al: reported man blind from birth had rhythm of 25 hrs.
  • Bio approach so focuses on bio factors :. scientific. But reductionist & determinist.
  • Issue of animals in research: generalisability.
  • Nature/Nurtute = En Pa/Ex Ze
  • Individual difference occurs :. Gender & Culture Bias.
  • Ethical Issues: socially sensitive as it affects peoples health.

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