✓ Exogenous Zeitgebers (AO1)

Question 1

What is Entrainment?

Answer 1

entrainment is the process of exogenous zeitgebers (external factors) in the environment resetting our biological clocks

the sleep/wake cycle is determined by an interaction of internal & external factors

Question 2

Light as an EZ?

Answer 2

light is a key exogenous zeitgeber

it resets the body’s main EP - the SCN

light also has an indirect influence on processes in the body such as hormone secretion (melatonin) & blood circulation

Question 3

Social cues & EZ?

Answer 3

new-born babies have free running cycles

by abt 16 weeks most babies are entrained onto the 24 hour sleep/wake cycle due to adults enforcing routine behaviour (e.g. mealtimes & bedtimes)

therefore to overcome jetlag, the best way would be to adapt to local times for eating & sleeping

Question 4

What 3 researcher did studies that support Exogenous Zeitgebers?

Answer 4

Campbell & Murphy
Steel et al
Shih-Yu Lee

Question 5

What was Campbell & Murphy’s study?

Answer 5

15 ppts were woken at various times during the night & a light was shone on the back of their knees

circadian rhythms were disrupted by up to 3 hours

suggests that light is a powerful EZ

don’t have to only apply to visual input but sun receptors too

Question 6

What was Steel et al’s study?

Answer 6

monitored individuals in the arctic w constant daylight for 6 weeks

ppts kept sleep logs

5/6 ppts developed free running cycles longer than avg. 24 hours cycle

Question 7

What was Shih-Yu Lee’s study?

Answer 7

mothers w premature babies in NICU can have more sleep disturbances
- due to both stress & the dim lighting
- desynchronises circadian rhythms

mothers were given bright light therapy over a 3-week period & sleep monitored

mothers reported improvement in sleep length/quality & less depressive symptoms