BIOLOGICAL RHYTHMS - CIRCADIAN RHYTHMS Flashcards
what 4 things must we remember for circadian rhythms?
biological rhythms
sleep/wake cycle
siffre’s cave study
other research
what are biological rhythms?
distinct patterns of changes in body activity to cyclical time periods influenced by exogenous zeitgebers and endogenous pacemakers
what is a circadian rhythm?
a biological rhythms subject to a 24 hour cycle regulating a number of body processes such as sleep/wake cycle and changes in the core body temperature
who has biological rhythms?
plants animals and people
why 2 things are biological rhythms governed by?
body’s internal biological clock - endogenous pacemakers
changes in the environment - exogenous zeitgebers
what is the most important exogenous zeitgeber?
daylight and this is shown through how we feel drowsy when it’s night-time and alert during the day
what is ‘free-running?’
if the biological clock was left to it’s own devices without the influence of external stimuli such as light
who tried to answer the question of ‘free-running’ and conducted research?
Siffre
what dud Siffre do?
spent several extended periods underground to study the effect of his bio rhy
what was siffre deprived of, and what did he have access to?
deprived of exposure to natural light and sound
access to adequate food and drink
how long did he spend in first 2 studies in the cave?
- 2 months in the cave of the alps
2. 10 years later, performed similar test for 6 months in a Texan cave
what happened in both of Siffre’s experiments?
‘free-running’ biological rhythm settled down to 25 hours though he did continue to fall asleep and wake on a regular schedule
who found similar results to Siffre?
Aschoff and Wever
what did Aschoff and Wever do?
ppts spent 4 weeks in WWII bunker w/ no natural light
what were the findings of Aschoff and Wever experiment?
all but 1 ppts had circadian rhythm of 25 hrs, one had 29 hrs
what do Siffre’s and Aschoff and Wever’s study show?
‘natural’ sleep/wake cycle could be longer than 24 hours, but trained by exogenous zeitgebers associated w/ 24 hrs day
who studied exogenous zeitgebers?
Folkard et al
who did Folkard et al study and what did they do?
12 ppl who agreed to live in a dark save for 3 weeks, went o be at 11:45 and waking up at 7:45
what did researchers to over the course of Folkard’s study?
gradually speeded up the clo9ck so the 24 hr day was eventually 22 hrs
what were the findings of Folkard’s study and what does this suggest?
only 1 ppt adjusted by to the new regime , suggested the existence of a strong free-running circa rhy cannot be easily overridden by exogenous zeitgebers
give 3 evaluations points for circadian rhythms?
+ practical application to shift work
+ practical application to drug treatments
- use of case-studies and small samples
a strength of circadian rhythms is that it has good practical application to…
shift work
what does knowledge about circadian rhythms given researchers a better understanding of?
adverse consequences that can occur as a result of their disruption known as desynchronization
what did Boivin et al find that shows affects of shift work?
night workers engaged in shift work experience a period of reduced concentration around 6 in the morning, a circadian trough that makes mistakes and accidents more likely
who conducted research to suggest a relationship between shift work and poor health?
Knutsson
what did Knutsson find?
shift workers are 3+ x likely to develop heart disease due to stress of adjusting to different sleep/wake cycles and poor quality of sleep throughout the day
therefore, practical application for circadian rhythms to shift work has…
economic implications in terms of how best to manage worker productivity
circadian rhythms also has high practical application for ____ _________
drug treatments
what do circa rhythms cooridnate that has an effect on…
number of body’s basic processes e.g heart rate, digestion and hormone levels having an effect on pharmacokinetics
what are pharmacokinetics?
the action of drugs on the body and how well they are absorbed and distributed
what does research into circadian rhythms reveal about drug treatments?
there are certain peak times during the day or night where drugs are likely to be at their most effective
what does circadian rhythms led to the developemnt of in drug treatments?
guidelines to do with the timing of drug dosing for a range of medication such as anti-cancer, cardiovascular, respiratory etc [ baraldo ]
a weakness of circadian rhythms is that…
studies of sleep/wake cycle involve small groups of ppts
what are ppts to representative of?
the wider population and limits the extent of menaingful generalisation
what does that even when the same person is studied there are factors that prevent general conc?
siffre most recent exp at age 60 shows his internal clock was slower than when he was a young man
