Circadian Rhythms Flashcards
What is a circadian rhythm?
Something that happens once in a 24 hour period
What are two circadian rhythms?
- Temperature
- Sleep-wake cycle
When is our body’s temperature lowest and highest?
- Lowest: at 4:30am (36°C)
- Highest: at 6:00pm (38°C)
What are the 7 steps of the sleep wake cycle?
1) Darkness falls
2) Optical chiasm
3) Stimulates SCN
4) Etimulates pineal gland
5) Produces melatonin
6) Brain activity falls
7) Sleep
What did Michel Siffre do?
Spent 6 months in an underground cave, there was no natural light and had no other external cues as to what form of day of day it was. He monitored his patterns of sleeping and waking by sending a message each morning and evening
What was Michel Siffre’s natural circadian rhythm?
Just over 24 hours but would sometimes rise to 48 hours
What did Aschoff and Wever do?
Placed 42 participants in an underground WWII bunker, pps lived singly for a period of 1 week to a month. Pps had to give a signal when the thought 1 hour had passed
What were Aschoff and Wever’s findings?
Most people displayed circadian rhythms of 24-25 hours, although some people displayed a 29 hour rhythm
What did Folkard do?
Tried to see what would happen if you alter the environmental time cues. A group of 12 people lived in an isolation unit for 3 weeks
What did the participants do?
Agreed to get up when it said 7:45am and go to bed at 11:45pm
How did Folkard study the participant’s circadian rhythms?
He set up the clock so that initially it ran as normal, but gradually began to speed up until 24 hours was passing in only 22 hours. Only 2 of the participants could keep up with this rhythm
