biological rythms Flashcards
what are biological rhythms?
patterns of changes in body activity conforming to cyclical time periods and influenced by endogenous pacemakers and exogenous zeitgebers
what are circadian rhythms?
a type of biological rhythm part of a 24-hour cycle
what are some examples of circadian rhythms?
sleep/wake cycle, body temperature
how is the sleep/wake cycle studied?
using isolation studies
How did Michel Siffre conduct research into the sleep/wake cycle?
first, he spent two months in a cave underground deprived of external sounds and natural light and time, he also later spent 6 months in a cave
what did Michel Siffre find?
his biological sleep/wake cycle adjusted to 24.9 hours but still slept on a regular schedule
What was Aschoff and Wever’s study?
ppt spent 4 weeks in a ww2 bunker with no knowledge of time or natural light
what did Aschoff and Wever find?
all but one participant (29 hours) had a regular cycle of 24-25 hours
what was Folkard et al’s study?
they studied 12 people in a bunker where they went to bed when the clock said 23:45 and woke when it said 7:45, over the course of the experiment the clock was spead up without the ppts knowledge until there were 22 hour days
what did Folkard et al find?
only one person adjusted comfortably to a 22 hour day
what can we conclude from sleep/wake cycle research?
there are free-running cycles which exist that can not easily be changed by exogenous zeitgebers
what are ultradian rhythms?
biological cycles that occur more than once a day
what are some examples of ultradian rhythms?
cycles of sleep stages, heartbeat, breathing rate
what are infradian rhythms?
biological cycles that occur less than once day
what has shift work research found?
- around 6 am there is a period of reduced concentration were mistakes and accidents are more likely
- shift workers are 3 ties ore likely to develop heart disease due desynchronisation and poor sleep during the day
what is the application of research into pharmacokinetics?
the time in the day in which the drug is taken is important due to differences in absorption, distribution and effectiveness at a different time of the day
- leading to guidelines for drug dosages
what are the strengths of research into shift work?
- understand the consequences of desynchronisation
- can be used to manage worker productivity, therefore benefiting the economy
what are some of the issues with sleep/wake cycle studies?
- small ppt numbers
- assumes artificial light will have no effect
- Czisler et al found dimmed light can extend the sleep/wake cycle to 28 hours
- no control of confounding variables e.g. humidity in the cave
- the role of exogenous zeitgebers may be overestimated
what can the sleep/wake cycle vary by at most?
13 to 65 hours
what are the problems with isolation studies?
they are extremely rare so could be seen to lack validity
