Biological rhythms Flashcards
What is a biological rhythm
A change in the body processes or behaviour in response to cyclical changes within the enviroment.
biological rhythm around 24h
Circadian
Biological rhythm less than 24h
Ultradian
Biological rhythms more than 24h
Infradian
endogenous pacemaker
body’s internal clock that regulates biological rhythms
Exogenous zeitgebers
External factors in the environment which reset our biological clocks.
The sleep wake cycle
the fact we feel drowsy ant night an alert in the day.
Siffre’s cave study
Isolated only eating and sleeping when his body told him to.
To discover the natural rhythms of life when living beyond time.
Settled into SW cycle of 25-30h.
Weakness for Siffre’s cave study
Case study
Aschoff and weaver
Bunker study for 4 weeks
settled into 25-27h rhythm
Conclusion of cave and bunker studies
Removing EZs increases length of sleep/wake cycle. We want to run on 25h but we are restrained to 24h.
Folkard cave study
Changing external cues. Changed clocks from 24 to 22 hours but pps struggled to settle down.
Limits how well EZs can rule SW cycle.
Limitations of research into circadian rhythms
Individual differences are magnified as small sample sizes.
Age is a confounding variable
Practical application of circadian rhythms research
Shift work. Decreases accidents and increases productivity
when to administer drugs
Control issues in circadian rhythms research
Artificial light not controlled
The mcClintok study
Observed synchronisation of menstrual cycles.
Asked 135 college girls living in halls to rack the first day of their periods for 3 months
day difference went from 6.4 to 4.6.
Weaknesses of the McClintok procedure
No control over diet and stress
Stern and McClintok study
Investigate other womans pheromones on the menstral cycle.
29 women- 9 donors gave sample (cotton pad under arm)
Women then smelt the pads.
68% of woman experienced changes in line with the donor
Pheremones act as a EZ
3 weaknesses of Stern and McClintok
small sample sizes so may be due to chance.
self report over onset of period
no control for stress and diet
Yang and Schank findings
in any group of people there will be times of synchrony.
causes of sad- melatonin
In winter months there is less sunlight and therefore we can have difficulty waking.
Has a knock on effect on serotonin
Lambert et al sunlight research
How sunlight helps depression.
Metabolism of serotonin is lowest in winter and therefore could cause SAD.
treating SAD
phototherapy- lightbox mimic the sun
goldman- phototherapy is as effective as antidepressants for treating depression
Could be placebo.
Ultradian rhythms example
stages of sleep
