BP- Ultradian and Infradian Rhythms Flashcards
What are ultradian rhythms?
A cycle that spans a period of less than 24 hours.
E.g five sleep stages
What are the stages of the human sleep?
1) Non-Rapid Eye Movement (NREM) sleep (which consists of stages one, two, three and four)
2) Rapid Eye Movement (REM) sleep (which is stage five)
How long does the human sleep cycle last?
90 minutes
What did Kleitman suggest about the BRAC (Basic Rest Active Cycle) ?
- He suggested that this 90 minute cycle continues when we are awake. -During the day, rather than moving through the sleep stages, we move progressively from a state of alertness into a state ofphysiological fatigue
Give advantages of the ultradian rhythms.
1) Ericsson et al found support for ultradian rhythms.
- They studied a group of elite violinists and found that group practice sessions were limited to 90 minutes at a time.
- Violinists frequently napped to recover from practise, with the best violinists napping more.
- The same pattern was found amongathletics, chess players and writers. This fits with the BRAC.
2) Our understanding of ultradian rhythms is supported by research.
- Dement and Kleitman monitored sleep patterns of nine adults in a lab testing EEG whole controlling effects of caffeine and alcohol.
- It was found that REM activity correlated with dreaming and brain activity.
- This demonstrates that our research of ultradian sleep cycles is accurate.
Give disadvantages of ultradian rhythms.
2) Tucker et al. (2007) suggests that there are individual differences in ultradian rhythmswhich are biologically determined and may even be genetic in origin. - Participants were studied over 11 consecutive days and nights in a laboratory environment. -The researchers assessed sleep duration, time taken to fall asleep and the amount of time in each sleep stage.
- They found differences in all of these characteristics.
What are infradian rhythms?
Infradian rhythms span a period of longer than 24 hours.
- They may last weeks, months, or even a year.
Give an example of infradian rhythms.
The menstrual cycle.
- Average is 28 days.
What is the infradian rhythm controlled by?
It is controlled by the human body (Endogenous pacemakers- hormones)
- The endogenous pacemakers of the menstrual cycle are oestrogen and other hormones.
Give advantages of the infradian rhythm.
1) Infradian rhythms can affect behaviour.
- Penton-Voak (1999) found that women express a preference for feminised male faces when choosing a partner for a long-term relationship.
- However, they showed a preference for masculinised faces during ovulation
2) Research support for the role of exogenous cues
- Russel et al collected samples of sweat from a group of women and applied it to the upper lip of a second group of women
- Even though the women were kept separate, it was found that their menstrual cycles became synchronised.
- Demonstrated that our understanding of infradian rhythms being influenced and regulated by biological chemicals such as pheromones is accurate.
- This increases is validity.
Give disadvantages for the infradian rhythm.
1) -The menstrual cycle is not only governed by infradian rhythms.
- When several women of childbearing age live together, and do not take oral contraceptives, their menstrual cycles synchronise.
- In one study samples of sweat were collected from one group of women and rubbed onto the upper lip of another group of women, their menstrual cycles became synchronised.
- This suggests that the synchronisation is affected by pheromones.
- Pheromones are a chemical substance produced and released into the environment byan animal which affectsthe behaviour of others of the same species.
2) Infradian rhythms relies on poor evidence.
- An issue is that is relies on poor and unscientific evidence.
- Menstrual synchronisation studies fail to take into account confounding variables such as stress, changes in diet and exercise.
- This weakens the cause and effect between pheromones and menstrual synchronisation.
- Also, these studies are often based on small scale samples of women, presenting population and generalisability issues. Relies of self reporting of menstrual cycles which might be inaccurate.
