Biopsychology Flashcards
What are infradian rhythms
Take longer than a day to complete
- the menstrual cycle
- seasonal affective disorder
What is the menstrual cycle
- a infradian rhythm
- governed by monthly changes in hormone levels which regulate ovulation
- the cycle refers to the first day of a womans period to the day before her next period
- the typical cycle takes around 28 days to complete
What happens during the menstrual cycle
- during each cycle, rising levels of the hormone oestrogen cause the ovary to develop an egg and release it (ovulation)
- after ovulation, the hormone progesterone helps the womb lining to grow thicker, readying the body for pregnancy
- if pregnancy does not occur the egg is absorbed into the body and the womb lining is shred
The menstrual cycle is an endogenous system what exogenous factors may influence the menstrual cycle
Cycles of other women
What researcher demonstrated how menstrual cycles may synchronise as a result of the influence of female pheromones
Stern and McClintock
What did Stern and McClintock discover
Demonstrated how menstrual cycles may synchronise as a result of the influence of female pheromones
What is a pheromone
Outline the study of Stern and McClintock
Aim; to show that the menstural cycle is influenced by pheromonal secretions from other women
Sample; 29 female university students with irregular periods, not taking birth control pill
Method; samples of pheromones were collected from 9 women (control group) at different stages of the menstrual cycle, via a cotton pad placed in their armpit. The pads were worn for 8+ hours to ensure pheromones were picked up. The pads were treated with alcohol and frozen, and were then rubbed on the upper lip of the other pps. On day 1, pads from the start of the menstrual cycle were applied to all 29 women, on day 2 they were given pads from the second day of the cycle etc.
Result; 68% of women experienced changes to their cycle which brought them closer to the cycle of their ‘odour doner’
What is seasonal affective disorder (SAD)
- depressive disorder which has seasonal patterns of onset, and is described and diagnosed as a mental disorder in the DSM
- main symptoms include a persistent low mood and general lack of activity in and interest in life
- often referred to as winter blues as the symptoms are triggered in the winter months where daylight hours are short
- it is a circannual rhythm as it happens yearly, but can also be classed as a circadian rhythm as SAD may stem from a disrupted sleep/wake cycle- due to prolonged period of daily darkness
What happens during SAD
- psychologists have hypothesised that the hormone melatonin is implicated in the cause of SAD
- during the night, the pineal gland secretes melatonin until drawn when there is an increase in light
- during winter, the lack of light in the morning means this secretion process continues for longer
- this is thought to have a knock on effect on the production of serotonin in the brain- a chemical linked to the onset of depression
What are ultradian rhythms and example
Occur many times in a day
- the stages of sleep
Describe The Stages of Sleep
5 distinct stages that span about 90 minutes
- each stage is characterised by a different level of brainwave activity which can be monitored using EEG
Describe stage 1 of sleep
- light sleep
- easily woken
- muscle activity slows down
- occasional muscle twitching
- brainwave patterns become slower and more rhythmic (ALPHA WAVES)
Stage 2 sleep cycle
- breathing pattern and heart rate slows
- slight decrease in body temperature
- brain waves become even slower as sleep becomes deeper (THETA WAVES)
Stage 3 of the sleep cycle
- deep sleep (slow wave sleep) begins
- brain begins to generate slow DELTA WAVES
Stage 4 of the sleep cycle
- very deep deeo
- difficult to wake someone
- rhythmic breathing
- limited muscle activity
- DELTA waves now have a greater amplitude than earlier wave patterns
Stage 5 sleep cycle
- rapid eye movement
- dreaming occurs
- muscles relax and body becomes in paralysed
- hear rate increases
- breathing is rapid and shallow
- brain activity speeds up to the point where it resembles the awake brain
