PSYA3- Biological Rhythms & Sleep (AO1)

Ultradian Rhythm
1. Spans less than a day and occurs more than once a day e.g. sleep stages, eating
  1. Sleep Stages: 90 min cycle
    1. 1) Lasts approx 15 mins. Reduced light ^ melatonin - inhibits wakefulness. EEG measurements indicate relaxations, reduced heart rate.
      1. 2) Lasts approx 20 mins. First point- truly sound asleep. EEG measurements indicate larger slower brain waves.
        3) Lasts 15 mins. EEG activity is characterised by long slow- delta waves with sleep spindles.
        4) Lasts 30 mins approx. Slow - wave sleep- long slow waves of EEG. The EOG & EMG show very little activity.
        5) Lasts approx 10 mins- first cycle -builds up to an hour by 4th/5th cycle. EEG activity is characterised by beta waves- relaxed waking state linked to dreaming.
Circadian Rhythm
1. Lasts about 24 hours e.g. Sleep wake cycle, Body temp
2. 1) Humans and mammals have an endogenous pacemakers - internal biological - suprachiasmatic nucleus (SCN) -lies in the hypothalamus -lies above optic nerve.
  1. 2) SCN sends signals to pineal gland-increase production melatonin at night- Melatonin induces sleep inhibiting brain mechanisms that promote wakefulness
Infradian Rhythm
1. Occurs for a period more than one day but less than one year e.g. Female Menstrual Cycle- lasts approx 28 days
  1. Female Menstrual Cycle (AO1)
    1. Driven by fluctuating hormone levels. Research suggests - pituitary gland releases hormones which stimulate follicle in 1 ovary to ripen egg- release oestrogen
  2. SAD (AO1)
    1. Infradian rhythms do not have to monthly- can occur once a yr. SAD can occur e.g. during winter months and people recover in the summer.
      1. Research shows- melatonin secreted -pineal gland = dark ; more darkness - the more melatonin. Research also shown- melatonin related to chronic depression. But SAD may be due- disruption to circadian rhythm e.g. go to bed earlier wake up later in dark
Circannual Rhythm
1. Occurs or fluctuates at intervals of approx one year e.g. Migration of birds
What controls Biological Rhythms?
1. Endogenous Pacemakers- Regulate your rhythms inside your body
2. Exogenous Zeitgebers- Regulate your behaviour outside your body
Disruption of biological rhythms
1. Shift Work
  1. - Decreased alertness - sleep deprivation - effects on health
2. Jet Lag
  1. Erroneous decision making - hard to make decisions due to jet lag.
  2. Less difficulty - travelling east to west (phase delay)
  3. More difficulty to adjust West to East (Phase Advance)
3. Real life applications: IDA
  1. Chernobyl, Exxon Valdez oil tanker grounding, space shuttle challenger
Lifespan changes in sleep
Functions of sleep
Sleep Disorders

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PSYA3- Biological Rhythms & Sleep (AO1)

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	Creado por Tayyaba Husain hace casi 10 años