Circadian Rhythms

Question 1

24 hour rhythms are regulated by

Answer 1

Endogenous and exogenous pacemakers

Question 2

What are 24 hour rhythms

Answer 2

• biological rhythms that change bodily activity to conform to a cyclical time period. Every cell has a clock that is synchronised by the super charismatic nuclei (SCN) in the hypothalamus (ENDOGENOUS PACEMAKER).

Question 3

The sleep-wake cycle

Answer 3

We feel drowsy at night and alert during the day - due to light (exogenous pacemaker) as light resets the SCN. Endogenous work together to keep us in time.

Question 4

Case study 1- Siffre

Answer 4

• Siffre spent extended periods in a cave (2 months and 6 months) to study effects on endogenous pacemakers.
• he was deprived of sunlight and noise.
• He found that his free running rhythm was 25 hours, not 24 and his sleep stayed regular (8 hours).

Conclusion: endogenous pacemakers have a significant influence on biological rhythms.

Question 5

Case study 2- Folkard

Answer 5

• 12 participants lived in a cave for 3 weeks, going to sleep at 11:45 and woken at 7:45.
• unknown to them, the researcher sped up the clock so a day eventually lasted 22 hours. The study found that only one person adjusted to this timing.
• this suggests that the existence of a strong, free running circadian rhythm

Question 6

AO3 STRENGTHS

Question 7

AO3 WEAKNESSES