Biological Rhythms: Infradian and Ultradian Rhythms Flashcards
What is an untraditional rhythm?
A biological rhythm with a frequency of more than one cycle in 24 hours
What is an infradian rhythm?
A biological rhythm with a frequency of less than one cycle in 24 hours
What are examples of infradian rhythms?
- Menstrual cycle
- Seasonal Affective Disorder (SAD)
What are examples of ultradian rhythms?
Sleep cycle
Describe the menstrual cycle:
- Levels of oestrogen causes ovaries to develop and release an egg
- Progesterone helps the womb lining to thicken, readying the body for pregnancy
- If no pregnancy then egg is absorbed and womb lining comes away hand leaves the body
What did Stern and McClintock (199) do?
- 29 women with irregular periods
- Pheromones were taken at different stages of cycle visual cotton pad
- Pads cleaned with alcohol and rubbed on lips of other participants
What did Stern and McClintock (1989) find?
68% of women experienced changes to cycle which brought them close to their ‘odour donors’
What is Seasonal Affective Disorder (SAD)?
Depressive disorder (low mood/activity) with a seasonal pattern
What is another type of rhythm does SAD come under other than infradian rhythm?
Circannual
What is released during the night which is linked to SAD?
Melatonin
Which gland is melatonin secreted from?
Pineal gland
What stimulus causes the release of melatonin?
The dark
Is the release of melatonin increased or decreased during the winter?
Increased
What knock-on-effect does melatonin have?
Effect secretions of serotonin
What type of rhythm is stages of sleep?
Ultradian
What is the stages of sleep?
- Occurs in 90-minute periods
- Divide into five stages
- Each stage characterised with a different level of brainwave activity using EEG
What are the five stages of sleep?
- Stage 1 & 2: light sleep
- Stage 3 & 4: difficult to rouse someone
- Stage 5: REM (rapid eye movement) sleep
What occurs at stage 1 & 2 of the stages of sleep?
- Light sleep
- Easily woken
- Slower and more rhythmic brainwaves (alpha waves)
- Becomes deeper (beta waves)
What occurs at stage 3 & 4 of the stages of sleep?
- Deep sleep (delta waves)
- Slow waves and greater amplitude
What occurs at stage 5 of the stages of sleep?
- Fast, jerky activity of eyes
- Body paralysed yet brain activity speeds up
How did research into the menstrual cycle show its evolutionary values?
- More advantageous for females to menstruate at the same time
- Offsprings can be collectively cared for
Who challenged whether there is an evolutionary value of all females menstruating at the same time?
Schank (2004)
What did Schank (2004) argue?
That too many females cycling at the same time increases the competition with males so avoidance of synchrony would appear adaptive evolutionary
What is the methodology issues with research into synchronisation studies?
- Too many confounding variables which may change menstrual cycle (e.g stress, diet etc.)
- Self-report method (may be inaccurate)
- Small samples
Who supports qualitatively different stages in sleep?
Dement and Kleitman (1957)
What did Dement and Kleitman (1957) do?
Monitored sleep patter of 9 people in a sleep lab
What did Dement and Kleitman (1957) find?
- Proof of sleep wake cycle
- Correlation between REM and dreaming
- REM is ultradian rhythm
What is the limitation of research using animal studies in pheromones?
- Extensive understanding of animals and the role of pheromones in sexual behaviour
- But limited in humans
What is the practical application of research into SAD?
Development of phototherapy (lightbox stimulating strong light in morning and evening to reset melatonin levels)
What may synchronise menstrual cycles?
Exogenous zietgebers
