[S] Biological rhythms Flashcards
(24 cards)
What is a biological rhythm?
An innate, biologically driven behaviour that is periodically repeated.
What does the hypothalamus do?
It influences our sense of time, and produces melatonin when it gets dark.
What does seasonal affective disorder do?
Affect a person’s melatonin production, producing more than necessary which makes them feel drowsy and exhausted.
What are exogenous zeitgebers?
External time-givers such as clocks.
What are endogenous pacemakers?
Internal cues such as hormones.
What are the four main types of biological rhythms?
Ultradian, circadian, infradian and circannual.
What is an ultradian rhythm?
A rhythm that spans less than and occurs more than once in a day, such as the sleep cycle.
What is a circadian rhythm?
A rhythm that lasts around 24 hours, such as the sleep/wake cycle.
What is an infradian rhythm?
A rhythm that lasts for more than a day but less than a year, such as the menstrual cycle.
What is a circannual rhythm?
A rhythm that occurs around once a year, such as the migration of birds.
What did Dement and Kleitman find?
People awoken in REM sleep were more likely to report that they were dreaming.
What did Friedman and Fisher find?
The Basic Rest Activity Cycle is a 90 minute cycle in eating and drinking behaviour.
What is a strength of research into ultradian rhythms?
There is a link between REM sleep and dreaming.
What is a weakness of research into ultradian rhythms?
Dement’s research was conducted in a laboratory so the results could have been affected.
What did Siffre find?
After spending 6 months living in a cave with no natural light, his sleep/wake cycle adjusted to 25 hours.
What did Aschoff and Wever find?
Participants placed in a WWII bunker without exogenous zeitgebers maintained a 24-25 hour sleep cycle.
What did Czeisler et al find?
24 men and women who lived in very subdued light could have their circadian rhythms lowered to 22 hours and extended to 28 hours.
What did Miles et al find?
A blind man had a circadian rhythm of 24.9 hours and exogenous zeitgebers had little effects on his rhythms and he had to take sedatives and stimulants in order to maintain a healthy rhythm.
What did Morgan find?
Bred mutant hamsters who to have a circadian rhythm of 20 hours and transplanted their suprachiasmatic nucleus to normal hamsters who then displayed the mutant rhythms.
What is a strength of research into ultradian rhythms?
There is lots of research, all supporting the same ideas making the theory more reliable.
What are two weaknesses of research into ultradian rhythms?
- Research is based on case studies.
2. Animal studies are unethical.
What did Russell et al find?
When several women live together and do not take contraceptives, their menstrual cycles synchronise.
What is a strength of research into infradian rhythms?
Russell’s study shows that biological rhythms can be controlled by exogenous cues.
What is a weakness of research into infradian rhythms?
Focuses on females.
