Biological Rhythms Flashcards
(34 cards)
what are biological rhythms?
an important influence on the way which body systems behave
What are biological rhythms governed by?
- The body’s internal biological ‘clocks’ which are called endogenous pacemakers
- External changes in the environment which are known as exogenous pacemakers
What are the 3 different types of biological pacemakers.
Circadian, ultradian and infradian
What is a circadian rhythm?
A biological rhythm that lasts about 24 hours, which regulates the bodily processes
What are the examples of circadian rhythms?
The sleep-wake cycle and core body temperature
What is the sleep-wake cycle controlled by?
The suprachiasmatic nucleus in the hypothalamus
Which exogenous zeitgerbers are involved with the sleep-wake cycle?
Light and darkness
When does the circadian rhythm dip and why?
2-4am and 1-3pm because that’s when we have our strongest sleep drive
What makes the dip in the circadian rhythms less intense?
If we’ve had enough sleep
What makes the circadian rhythms ‘free-running’?
It will last 24-25 hours with external cues such as light
In what circumstances will the circadian rhythm be disrupted?
Jet lag and night shifts
When is the core body temperature the lowest and highest?
Lowest is 4:30am and highest is 6pm
Why does the core body temperature dip and rise at its specific times?
It dips during sleep and rises during the last hours of sleep to promote the feeling of alertness in the morning
When is there a small drop in the core body temperature and what does this cause?
2pm and 4pm, which causes people to feel sleepy
What is the study supporting circadian rhythms?
Siffre (1975) - spent 6 month in a cave with only artificial light to navigate around the cave. He lost track how long he’d spent in the cave - he thought it was 1 month but it was 6
What are the evaluation points for circadian rhythms?
+ Supporting evidence - Siffre 1975
- Contradictory evidence to Siffre 1975 - Czeizler et al
- Supporting evidence has low population validity
+ Practical application - shift work
What is an infradian rhythm?
A biological rhythm that has a frequency of less than one cycle in 24 hours
What are the examples of an infradian rhythm?
Menstrual cycle and seasonal affective disorder
What is seasonal affective disorder (SAD)?
A depressive disorder that is triggered during the winter months when the number of daylight hours become shorter
What is the study for infradian rhythms -menstrual cycle?
McClintock and Stern (1998)
What was the study of McClintock and Stern 1998?
He got 29 women who had irregular periods, sampled their pheromones and rubbed it on another women upper lip - 68% of women experienced changes to the period cycle
What are the evaluation points for McClintock and Stern 1998?
- Small sample size - 29 women
- Correlational - no cause or effect
- Only 68% of women experienced changes
- Methodological issues
What are the evaluation points for infradian rhythms?
+ Supporting research - McClintock and Stern 1998
+ Practical application - SAD therapy
What is an ultradian rhythm?
A biological rhythms that has a frequency of more than one in 24 hours
