Biological Rhythms (Biopsychology) Flashcards
(22 cards)
Circadian Rhythm
A biological rhythm that lasts 24 hours
Regulates sleep and wake cycles, the release of hormones and varying our body temperature
Endogenous pacemakers (EP)
Internal body clocks that keep biological processes to time
Exogenous Zeitgebers (EZ)
External cues that entrain body clocks to match the environment
EP and EZ of the sleep wake cycle
EP - SCN
EZ - Light
SCN
When light is detected by the SCN it sends a signal to the pineal gland, stopping the production of melatonin
Melatonin
Hormone that results in a sleep response
Light
Primary EZ in sleep wake cycle
Positive evaluations of Circadian Rhythms
Siffre lived in a cave for 6 months which had no natural light or other potential EZ’s (clocks)
His body clock (EP) maintained a regular cycle of 25 hours without EZs
Suggesting the EP for the sleep wake cycle is free-running but needs entrainment to keep the 24 hour day-night cycle
Negative Evaluations of Circadian Rhythms
The use of artificial lights in isolation experiments on the sleep wake cycle has been criticised
Suggesting the artificial light disrupted the free running circadian rhythm measurements by acting as an EZ
Infradian rhythms
Biological rhythm that takes longer than 24 hours to complete
menstrual cycle and SAD
SAD
When the emotional mood lowers in winter and improves in summer
Menstrual cycle
28 day cycle in which ovulation results in a releasing of the egg and the thickening of the womb lining and losing the womb lining during menstruation
Regulated by oestregen (pre-ovulation) and progesterone (post-ovulation) which act as endogenous pacemakers, acting as an internal body clock
Infradian Rhythms Evaluation
McClintock found 135 women who lived in the same dormitory appeared to synchronise their cycles
Suggesting the mentrual cycle infradian rhythm synchronises
Trevethan found cohabitating lesbians did not synchronise countering McClintock
Ultradian rhythms
Biological rhythm that takes less than 24 hours to complete one cycle
Stages of Sleep
Sleep Cycle Stage 1
Non-REM sleep: transition from wakefulness to sleep. Last less than 10 minutes and is marked by slowing heartbeat, breathing and eye movements as well as relaxing of muscles.
Alpha brain waves
Sleep Cycle Stage 2
Non-REM sleep: is the period of light sleep before you enter deeper sleep. Lasts roughly 20 minutes. Further slowing of heart rate, breathing and the brain begins to produce bursts of rapid, rhythmic brain wave activity known as sleep spindles.
Theta brain waves
Stage 3
Final stage of non-REM sleep: deepest period of sleep and lasts 20-40 minutes. Your heart rate and breathing are at the lowest levels and your muscles are so relaxed that it may be hard to awaken you
Delta brain waves
REM (Stage 4 of the sleep cycle)
Occurs 90 minutes after sleep onset and is much deeper sleep than any of the stages of non-REM. Defined as rapid eye movement and an almost complete paralysis of the body.
REM brain waves
Stages of sleep and their brain waves
1 - Alpha
2 - Theta
3 - Delta
4 - REM
Entrainment
• process of resetting the biological clock in line with external time cues
• synchronises the circadian rhythms
Positive Evaluations of Ultradian Rythms
Dermot + Kleitman recorded the brain activity of 33 ppts during sleep using EEGs
Brain waves followed a cyclic activation pattern supporting the theory that the stages of sleep are an Ultradian Rhythm with distinct features at each stage
Negative Evaluations of Ultradian Rhythms
Sleep stages have individual differences. Babies spend 80% of sleep in REM compared to 25% for adults
Suggests stages of sleep adapts to the needs of the individual
