Biological Rhythms Flashcards
What are all biological rhythms governed by?
The bodies internal clock- endogenous pacemakers
Environmental influences- exogenous pacemakers
What type of rhythms occur for multiple times during the day?
Ultradian rhythms
What type of rhythms take longer than one day?
Infradian rhythm
What are circadian rhythms?
They last about 24 hours a day for example they are the sleep wake cycle and core temperature
What is the sleep wake cycle?
Our bodies feel awake during the day and drowsy at night and this is an effect of daylight on the body
What can daylight be known as in regards to the sleep wake cycle?
Exogenous zeitgyber
What would the sleep wake cycle be like without daylight?
It could be argued that we would not know if it was day or night- would we go to sleep at the same time?
Siffre Case Study?
A man who spent several extended periods under ground to study the effects of his biological rhythms. He was deprived of natural exposure to light and sound but had access to adequate food and drink
Siffre results?
He resurfaced in mid September 1962 but believed it was August
His bio rhythms had settled down to one that was just beyond the usual 24 hours however he did continue to fall asleep and wake on a regular schedule
Aschoff and Wever?
He convinced a group of participants to spend 4 weeks in a WW2 bunker which was deprived of natural light- all but one participant had circadian rhythms of 24-25 hours
What does the study by Aschoff and Wever suggest?
That the natural sleep wake cycle may be longer that 24 hours but it is trained by exogenous zeitgybers with a 24 hour day such as daylight hours and mealtimes
Folkard?
Studied a group of 12 people who agreed to live in dog kennels for 3 weeks retiring to bed when the clock said 11-45 and rising when it said 7-45. Over the study the researchers gradually sped up the clocks so that the 24 hour day only lasted 22 hours.
Folkard results?
Not one of the participants were able to adapt to the new regime. This suggests that circadian rhythms are rigid attitudes and hard to overcome by changes in the external environment
By how much does core body temp vary?
2 degrees
When is core body at lowest?
4 in morning - 36 degrees
When does core body temp peak?
Around 6 in evening - 38
What does body temp correlate to?
Better cognitive performance- when we are warmer we are thought to perform to a higher standard
Folkard et al- body temp?
Demonstrated how children who have stories read to them at 3pm showed superior recall and comprehension after a week compared to children who heard the same story at 9am
Gupta?
Found improved performance on an IQ test when participants were assessed at 7pm as opposed to 2pm and 9am
What is a practical application of circadian rhythms? E
We now have a better understanding of the adverse consequences that occur as a result of their disruption. Night workers engaged in shift work experience a reduced level of concentration at 6AM ( the circadian trough) meaning that accidents are more likely to happen
Bovin? E
Research has suggested a link between shift work and poor health as shift workers are 3 times more likely to develop heart disease due to the stress they experience when adjusting to new sleeping patterns and lack of poor quality sleep during day
Knutsson 2003? E
Research may have economic implications in terms of how best to manage worker productivity
What do circadian rhythms affect within the body?
Heart rate, digestion and hormone levels
How has research influenced pharmocokinetics? E
Research has shown that there are peak times within the day or night when drugs are likely to be most effective- this has led to the guidelines to do with the timing of drugs for a whole range of medications including anti-cancer and anti-epileptic drugs
Why are case studies that provide research into CR limited? E
Tend to involve small groups of participants or single individuals- these people may not be representative of a whole population and limits the extent that meaningful generalisations can be made
