Circadian rhythms Flashcards
(6 cards)
AO1 circadian rhythms- SW
C R are driven by our body clocks, found in all cells of the body, synchronised by the C pacemaker- SCN in the hypothalamus, reset so body is synchronised with the environment, lasts 24 hours
- Entrainment process- light provides the primary input to this system, setting body to correct time, light receptors in the scn send messages about environment light levels direct to the SCN
-SW C dictates when we are asleep and awake using external signals ( L+ D) , sleep drive dips happen from 1-3pm and 2-4am
Homeostatic drive for sleep inc during day as energy is used up, circadian rhythm keeps us awake if theres daylight
- Hormone release is also dependent on a c rhythm , production and release of M peaks during dark hours and lowers during the day
SE Light AO3
- SE hughes 1977 tested CH on 4pp stationed at the british antarctic station
During feb, end of the antarctic summer cortisol levels followed a familliar pattern reaching highest point as the participants awoke - After 3 months of continuous darkness the pattern changed with peak levels of cortisol being at noon rather than as the men awoke
- Suggests extreme levels of daylight may be responsible for variation in C H release
AO3- individual differences
Ind diff in CR
Research shows circadian cycles can vary from 13-65 hours Czeisler et al 1999
Cycle onset can also vary individuals seem to be innatley different when CR reach their peak Duffy et al 2001, shows why people wake and sleep at diff times
AO3 research methodology limitation
LE- Early research studies are flawed when estimating the cycle of the human CR
- Most studies pp where isolated from variables which may affect the CR such as daylight, clocks and radios, but were not isolated from artificial light as they thought this would not effect the CR
- Research shows this is false- czeisler 1999 changed cr from 28hr to 22hr using artificial lighting, showing past studies have been counfounded by presence of artifical light
Real word app
Chronotherputics shows how timing affects drug treatments
specific time a drug is intaken is very important as it can have a significant impact on the treatment success , right conc at right time
Chronotherputic meds have a novel drug delivery system, adminstered before person goes to sleep, but may not release until a vunerable period in the morning
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