Biological rhythms

Question 1

Circadian rhythms

Answer 1

Biological rhythms that occur approximately every 24 hours, such as the sleep/wake cycle.

Question 2

Infradian rhythms

Answer 2

Biological rhythms that occur less frequently than once every 24 hours, such as the menstrual cycle.

Question 3

Ultradian rhythms

Answer 3

Biological rhythms that occur more frequently than once every 24 hours, such as the stages of sleep.

Question 4

Endogenous pacemakers

Answer 4

Internal body clocks that regulate biological rhythms, such as the suprachiasmatic nucleus (SCN) for the sleep/wake cycle.

Question 5

Exogenous zeitgebers

Answer 5

External environmental cues that influence biological rhythms, such as light and social cues in the sleep/wake cycle.

Question 6

Sleep/wake cycle

Answer 6

A circadian rhythm regulated by the interaction of endogenous pacemakers (like the SCN) and exogenous zeitgebers (like light).

Question 7

Suprachiasmatic nucleus (SCN)

Answer 7

A cluster of nerve cells in the hypothalamus that acts as the main endogenous pacemaker, regulating the sleep/wake cycle.

Question 8

Melatonin

Answer 8

A hormone released by the pineal gland that promotes sleep, influenced by the SCN and light exposure.

Question 9

Phase delay

Answer 9

A disruption to the circadian rhythm where the sleep/wake cycle is pushed later, common in jet lag when traveling west.

Question 10

Phase advance

Answer 10

A disruption to the circadian rhythm where the sleep/wake cycle is pushed earlier, common in jet lag when traveling east.

Question 11

Light as a zeitgeber

Answer 11

The most important exogenous zeitgeber for regulating the sleep/wake cycle, affecting the SCN and melatonin release.

Question 12

Social cues

Answer 12

Exogenous zeitgebers such as meal times and social interactions that help regulate biological rhythms.

Question 13

Menaker et al (1978)

Answer 13

Found that lesions to the SCN in hamsters resulted in disrupted circadian rhythms, highlighting the role of the SCN as an endogenous pacemaker.

Question 14

Aschoff and Wever (1976)

Answer 14

Placed participants in a WWII bunker without natural light and found that circadian rhythms extended slightly beyond 24 hours, indicating the role of endogenous pacemakers in the absence of exogenous zeitgebers.

Question 15

Pengelly and Fisher (1957)

Answer 15

Demonstrated hibernation-like behavior in squirrels even in constant environmental conditions, showing that endogenous rhythms can persist without external cues.

Question 16

Schwartz et al (1995)

Answer 16

Found that baseball teams traveling westward performed better than those traveling eastward, likely due to the effects of phase delay being easier to adjust to than phase advance.

Question 17

Wegman et al (1986)

Answer 17

Reported that circadian rhythms adapt more quickly when traveling westward compared to eastward, supporting the idea of easier adjustment to phase delays.

Question 18

Czeisler et al (1982)

Answer 18

Showed that exposure to bright light could reset circadian rhythms, demonstrating the significant role of light as an exogenous zeitgeber.

Question 19

Evaluation of research: practical applications

Answer 19

Research on biological rhythms has practical applications, such as improving shift work schedules to reduce health risks (e.g., night shifts disrupting circadian rhythms).

Question 20

Evaluation of research: artificial environments

Answer 20

Many studies, such as those by Aschoff and Wever, involve artificial environments, reducing ecological validity.

Question 21

Evaluation of research: animal studies

Answer 21

Animal studies, such as Menaker et al., provide insights into the role of endogenous pacemakers but may lack generalizability to humans.

Question 22

Evaluation of research: individual differences

Answer 22

Individual differences in circadian rhythms, such as ‘morning larks’ and ‘night owls,’ are often overlooked in research.

Question 23

Evaluation of research: managing jet lag

Answer 23

Studies like Czeisler et al. have shown how exogenous zeitgebers like light can be used to manage jet lag and improve sleep hygiene.