Biological Rhythms Flashcards
Biological rhythms
Controlled by internal body clocks (endogenous pacemakers) and external cues (exogenous zeitgebers)
Circadian rhythms
Biological rhythms, subject to a 24 hour cycle
Two examples of circadian rhythms
Sleep/Wake cycle
Core body temperature
The sleep/wake cycle
Governed by daylight and by biological clock (SCN), gets light information from the eyes
Siffre’s cave study
His free running rhythm extended slightly to 25 hours when deprived of daylight
Other research on circadian rhythms
(Support for exogenous Zeitgebers)
Support for exogenous zeitgebers entraining internal clock (Aschoff and Weavers, bunker, natural rhythm longer)
Other research on circadian rhythms
(Support for endogenous cues)
Support for endogenous cues if difference too big (Folkard cave with 22 hour day)
Biological rhythms evaluation points- Shift work
STRENGTH
Reduced concentration at 6 am, more accidents (Boivin) Heart disease three times more likely (Knutsson)
Biological rhythms evaluation points- Counter point to shift work
LIMITATION
Studies are correlational, effects may be due to disruptive social routines (Solomon)
Biological rhythms evaluation points- Medical treatment
STRENGTH
Timing of drugs (Chronotherapeutics), aspirin more effective at night for a heart attack (Bonten)
Biological rhythms evaluation points- Individual differences
LIMITATION
Cycle length is vary (13 to 65 hours, Czeisler), ‘larks’ and ‘owls’ (Duffy), generalisation may be meaningless
Infradian rhythms
Bodily rhythm that takes more than 24 hours to complete
What are the two examples of Infradian rhythms
- Menstrual cycle
- Seasonal Affective Disorder
The menstrual cycle
Oestrogen regulate ovulation, progesterone readies the body for pregnancy (Endogenous factors)
Synchronising the menstrual cycle
Menstrual cycle is synchronised through pheromones, exogenous factor
(Stern and McClintock)
Seasonal affective disorder
Form of depression triggered in the winter months and regulated by melatonin, a circannual rhythm
Infradian rhythms evolution points- Evolutionary basis
STRENGTH
Synchronisation may have an adaptive function, leads to shared care for babies
Infradian rhythms evolution points- Methodological limitations
LIMITATION
Mini confounding variables not controlled to synchronisation maker by chance (Trevathan)
Ultradian rhythms
Bodily rhythm that takes less than 24 hours to complete
Stage 1 and 2 of the ultradian rhythms
Alpha waves and sleep spindles
Stage 3 and 4 of ultradian rhythms
Deep sleep in Delta waves
Stage 5 of ultradian rhythms
R.E.M. (Rapid Eye Movement) sleep theta waves
Ultradian rhythms evolution points- Improved understanding
STRENGTH
SWS reduces the age, explains issues in old age e.g. reduced alertness (Van Cauter)
Ultradian rhythms evolution points- Individual differences
LIMITATION
Differences found in duration of each leap stage, particularly stages 3 and 4
(Tucker)
