Biological rhythms Flashcards
What are biological rhythms?
Changes in body activity dependent on cycles
What two factors regulate biological rhythms?
Endogenous pacemakers
Exogenous zeitgebers
What is a circadian rhythm?
A type of biological rhythm that is subject to a 24 hour cycle
What is an example of a circadian rhythm?
The sleep/wake cycle
How long did Siffre spend in a dark cave?
6 months
How did Siffre’s sleep/wake cycle change?
It was erratic at first, but then became 25 hours long
What does Siffre’s results suggest?
That the circadian rhythm is free running, which means it’s not affected by exogenous zeitgebers
How long were the participants of Folkard et al’s study in a dark cave?
3 weeks
How did the researcher of Folkard et al’s study try to influence the circadian rhythm of the participants?
He sped up the clock, so a day eventually lasted 22 hours
How many participants adjusted to the change in timings in Folkard et Al’s study?
1
What do the results of Folkard et Al’s study suggest?
That our circadian rhythms cannot be easily influenced by external factors
What is a strength of the research into the sleep/wake cycle?
Real life application - shift workers have a better understanding of how changing rhythms affects their productivity
What is a limitation of the Case Studies of sleep/wake cycles?
Lack ecological validity - rare that people are in the dark for such extended periods of time
What are infradian rhythms?
Cycles that take longer than 24 hours
What are 2 examples of infradian rhythms?
The menstrual cycle
Seasonal affective disorder
How is the menstrual cycle governed?
Through changes in hormone levels which regulate ovulation
Who were the participants of Stern and McClintock’s research?
29 women with irregular periods
How many women did Stern and McClintock take pheromones from and how did they do it?
9
They had a pad under their armpit for 8 hours at different parts of their cycles
What did Stern and McClintock do with the pheromones from the 9 women?
They rubbed them onto the upper lips of the other 20 participants on the corresponding days of their cycle
What did Stern and McClintock find?
68% of women experienced changes to their cycle and started to sync with their “donor”, suggesting that the menstrual cycle can be influenced by other women
What is seasonal affective disorder?
A depressive disorder which has seasonal patterns
What is the cause of seasonal affective disorder?
More melatonin is secreted during winter months due to the lack of daylight. This is thought to have an effect on the production of serotonin in the brain.
What is a limitation of the research into menstrual cycle syncing?
There are lots of other factors that influence the menstrual cycle such as stress/diet, so we can’t be sure it’s due to pheromones
How has research into seasonal affective disorder been applied to the real world?
Phototherapy is a treatment for seasonal affective disorder (resets melatonin levels)
What are ultradian rhythms?
Biological rhythms taking less than 24 hours
What is an example of an ultradian rhythm?
The sleep cycle
How many stages are in the sleep cycle?
5
How long is one sleep cycle?
90 minutes
Which stages of sleep are the ‘light sleep’ stages?
1 and 2
Which stages of sleep are the ‘deep sleep’ stages?
3 and 4
Which stage of sleep is ‘REM sleep’?
5
What does REM stand for?
Rapid Eye Movement
Which waves are present during stage 1 of the sleep cycle?
Alpha
Which waves are present during stage 2 of the sleep cycle?
Theta
Which waves are present during stages 3 and 4 of the sleep cycle?
Theta
During ‘light sleep’ it is…
Easy to be woken up
During ‘deep sleep’ it is…
Difficult to be woken up
In which stage of sleep does dreaming occur?
5 (REM)
What is a strength of the research into the sleep cycle?
It is all scientific and objective (EEGs used)
