Circadian rhythm STUDIES

Question 1

Siffre 1962 cave

Answer 1

6 months in a cave with no exogenous zeitgebers, found that his rhythm was consistently 25h, though experienced anomalies of up to 48 hours. Implies that endogenous pacemaker, SCN keeps roughly a 25 hour rhythm when body is deprived of exogenous zeitgebers

Question 2

Hughes 1977 British Antarctic Station

Answer 2

Participants at the BAS experienced changes to their cortisol cycle, peaking at 630am. Natives noticed no difference after several months of darkness.

Question 3

Czeisler 1999

Answer 3

People’s circadian rhythms vary from 13 to 65 hours. Rhythms can be altered from 22 to 28 hours using dim lighting. Implies that rhythms are different with everyone and can be altered using light.

Question 4

Evans and Marain 1996

Answer 4

Chronotherapeutic treatments like heart attack prevention medicine can be taken at night and not kick in until a vulnerable period at 6am. This implies a real world application to circadian rhythms.

Question 5

Buhr 2010 temperature

Answer 5

Temperature, rather than light is more important in setting a circadian rhythm clock. Temperature causes tissue activity, inactivity and affects the body clock. Implies that temperature, rather than light may be playing a major part in the circadian rhythms