Circadian Rhythms Flashcards
What are biological rhythms
Distinct patterns of changes in body activity that conform to cyclical time periods
What is a circadian rhythm
A type of biological rhythm that recurs approximately every 24 hours, which regulates a number of body processes
What are the 3 main body processes circadian rhythms regulate
- Sleep-wake cycle
- Core body temperature
- Hormone production
What do we mean by a ‘free-running’ sleep-wake cycle
It will maintain a cycle of about 24-25 hours even in the absence of external cues
Which research study showed support for a ‘free-running’ circadian rhythm
Michel Siffre’s cave study (1962)
Describe Michel Siffre’s cave study
- he spent several extended periods underground with no external cues to guide his rhythms
- found that his ‘free-running’ circadian rhythm was 25 hours
How does Siffre’s study show support for circadian rhythms
Shows that we have internal rhythm which guides our sleep-wake cycle in the absence of external cues
How does our circadian rhythm control release of hormones
- controls release of melatonin to make us feel awake and asleep
- during darkness- high levels of melatonin released to make us feel happy
- when its light melatonin drops to wake us up
How does our circadian rhythm control our core body temperature
- drop in body temp makes you feel sleepy (between 2 and 4pm and at 4:30am)
- body temp rises towards last hours of sleep to promote alertness
Between which times do we have our strongest dips in our sleep/wake cycle
Between 2 and 4am and 1 and 3pm
