Biopsychology: Biological Rhythms Flashcards
What is a circadian rhythm?
Biological rhythms, subject to a 24 hour cycle, that regulate internal processes e.g sleep/wake cycle.
Give two examples of a circadian rhythm:
Sleep/wake cycle
Changes in core body temperature
What are endogenous pacemakers
The body’s internal biological ‘clocks’
What are exogenous zeitgebers?
External changes in the environment
Who conducted research into the sleep/wake cycle?
Siffre
What did Siffre do to investigate the impact of the sleep/wake cycle and what did he find?
- Spent extended periods of time underground in a cave, where changes in natural light and sound did not occur.
- His biological rhythm was around 25 hours, with him waking up and sleeping in a regular schedule
What are the three evaluation points for Siffre’s research into the sleep/wake cycle:
1) Shift work (S)
2) Medical treatment (S)
3) Individual differences (L)
Explain shift work (S) as an evaluation point for Siffre’s research into the sleep/wake cycle
- Provide an understanding of the impacts of disrupting circardian cycles
- Boivin found that night shift workers were more likely to make mistakes than day shift workers (due to decreased concentration) , and were x3 more likely to develop heart disease
Explain medical treatment(S) as an evaluation point for functional recovery:
-Research into circadian rhythms has improved medical treatments.
- Advanced the field of chronotheraputics, where medical treatment is given according to a person’s biological rhythms.
- Can help increase the effectiveness of a drug e.g. aspirin is more effective when taken at night as most heart attacks occur in the morning.
Explain individual differences (L) as an evaluation point for research into the sleep/wake cycle:
- Generalisations are difficult to make as individual differences in sleep/wake cycles occur.
- Difficult to use the research data to discuss anything more than averages.
What is an infradian rhythm?
Type of biological rhythm where less than one cycle occurs in 24 hours e.g. menstrual cycle, SAD.
What is an ultradian rhythm?
Type of biological rhythm where more than one cycle occurs in 24 hours e.g. sleep cycle
Who investigated the impact of endogenous and exogenous factors on biological rhythms via the menstrual cycle?
Stern and McClintock
What did Stern and McClintock do to investigate the impact of endogenous and exogenous factors on biological rhythms via the menstrual cycle and what did they find?
- Gathered 29 women with irregular periods and collected samples of their pheromones at different stages of the menstrual cycle via a cotton pad.
- Pads were rubbed on the upper lip of the other participants according to the day of their MC (e.g. on day one they got a pad from the first day of their MC, on day two they got a pad from second day)
- Found that 68% of women experiences changes in their cycle which brought them closer the cycle of their ‘odour donor’
Explain the theory behind the cause of SAD due to disruptions in infradian rhythms:
- During the night, the pinael gland secretes melatonin until dawn where there is an increase in light.
- During winter the lack of light in the morning means this secretion process happens for longer.
-This is thought to have a knock-on effect on the production of serotonin in the brain- leading to the onset of depressive symptoms.
Give two examples of infradian rhythms:
- Menstrual cycle
- SAD
Give one example of an ultradian rhythm:
Stages of sleep (sleep cycle)
There are __ main stages of sleep in the sleep cycle, with each whole cycle lasting around ___ minutes.
5
90
What happens in stage 1 of the sleep cycle?
- Light sleep where the person may be easily woken
- Alpha waves are present (high frequency, short amplitude)
What happens in stage 2 of the sleep cycle?
- Alpha waves continue
- Occasional random changes in sleep spindles
What happens in stage 3 and 4 of the sleep cycle?
- Deep sleep (slow wave sleep) where it is difficult to wake the person up.
- Delta waves are present (Lower frequency, higher amplitude)
What happens in stage 5 of the sleep cycle?
- The body is paralysed yet brain activity closely resembles that of the awake brain.
- Theta waves are present.
- REM occurs- can result in dreams.
What are the three evaluation points for infradian rhythms:
1) Evolutionary basis (S)
2) Real world application (S)
3) Methodological limitations (L)
Explain evolutionary basis (S) as an evaluation point for infradian rhythms:
- The menstrual synchrony research may be used to explain natural selection
- Menstrual synchrony is thought to have evolutionary value as it may have been advantageous for women who menstruate together to get pregnant at the same time.
- Allow for infants who have lost their mothers to have access to breast milk- improving their chances of survival.
Explain real world application (S) as an evaluation point for infradian rhythms:
- One of the most effective treatments for SAD is a light box that simulates very strong light to reset the body’s internal clock.
- Effective in around 80% cases- (yet high relapse rate - 46%)
- Preferred treatment over antidepressants
Explain methodological limitations (L) as an evaluation point for infradian rhythms:
- Menstrual synchrony studies were flawed.
- Confounding variables that could have impacted the P’s menstrual cycle were present e.g. stress, exercise, diet.
- Any supposed synchrony could have just been due to chance.
What are the three evaluation points for ultradian rhythms:
1) Improved understanding (S)
2) Scientific methods (S)
3) Individual differences (L)
Explain improved understanding (S) as an evaluation point for ultradian rhythms:
- Research into ultradian rhythms has improved our understanding of age-related changes in sleep.
- Sleep scientists have observed that deep sleep reduces with age.
- The resulting sleep deficit may explain issues in old age, such as reduced alertness - which can be practically treated through medications
Explain scientific methods (S) as an evaluation point for ultradian rhythms:
- Conducting sleep studies in a lab allows for extraneous variables that may affect sleep to be controlled e.g. noise, temperature
- Increases internal validity of the study (not necessarily externally valid though - do second sleep study in Ps home as well to counteract this)
Explain individual differences (L) as an evaluation point for ultradian rhythms:
- Research shows that there is are significant variations between peoples sleep cycles, especially in stages 3 and 4.
- Tucker et al suggests these stages are likely to be biologically determined- making it difficult to describe ‘normal sleep’ in a meaningful way.
