Booklets 10 and 11 Flashcards
What are infradian rhythms?
Biological rhythms that are greater than a day, but less than a year (such as weekly or monthly)
What is an example of an infradian rhythm?
The menstrual cycle
What is the menstrual cycle?
This is the cycle that regulates ovulation. It is mainly driven endogenously and regulated by hormone changes.
Rising levels of oestrogen cause the development and release of an egg from the ovaries and progesterone causes the womb lining to grow thicker. If pregnancy does not occur, menstrual flow happens.
The cycle refers to the time between the first day of a period and the day before her next period
What is the research support for the menstrual cycle being influenced by exogenous zeitgebers?
One study found that female menstrual cycles become synchronised through pheromone exposure.
The pheromones from nine women at different days during their menstrual cycle were acquired through pads and then treated with alcohol and frozen.
On day one, the pads from the start of the mental cycle were rubbed on the upper lip of the other 20 participants and so on.
68% of women experience changes to their mental cycle in line with the odour donors.
What is the evaluation of infradian rhythms?
Confounding variables in synchronisation studies. A woman’s menstrual cycle can be changed by stress, diet and exercise.
Further research support from one study where a woman spent three months in a cave with no natural light and her menstrual cycle shortened. This suggests the lack of light affected her menstrual cycle.
An advantage of synchrony research is evolutionary value. It may be advantageous for females demonstrate together so that if babies lose their mothers during childbirth they still have access to breastmilk improving their chances survival.
What are ultradian rhythms?
Biological rhythms that have more than one cycle in 24 hours
What is an example of an ultradian rhythm?
Human sleep patterns
How many stages of sleep are there?
Five stages, they repeat themselves every 90 minutes throughout the night.
Four stages of NREM and the final stage of REM sleep
What is each stage of sleep characterised by?
Levels of brainwave activity that can be measured by an EEG.
What are stages one and two of the sleep cycle?
These are the light sleep stages were a person can be easily woken.
Stage one is defined by Alpha waves and stage two by Alpha with sleep spindles.
What are stages three and four of the sleep cycle?
These are deep sleep where it is more difficult to wake somebody than stages one and two.
Both are defined by Delta waves
Stage four is when most of the bodies physiological repair work is undertaken.
What is stage five of the sleep cycle?
This is REM sleep or dream sleep. The brain and eyes are active and brain activity closely resembles that have an awake brain.
Theta waves are produced
Dreams are most often experienced during REM sleep.
What is the evaluation of ultradian rhythms?
Research support where Randy Gardner stayed awake for more than 200 hours. Afterwards he only recovered 25% of his lost sleep after several nights He recovered 70% of stage four sleep and 50% of REM sleep. This shows the importance of REM sleep and suggest flexibility in the sleep cycle.
There is innate individual differences in ultradian rhythms so general laws cannot be established, one study in a controlled lab setting found that there were significant differences in duration of each stage for participants.
Research can help understanding of age related changes in sleep. All the people have reduced stage three and four sleep, which is where. the bodies physiological repairs happen which makes various issues with old age.
What is the process of the sleep wake cycle?
Light (exogenous zeitgeber) detected by optic nerve
This information is received by the SCN
SCN send signals to the pineal gland
Melatonin production in the pineal gland is inhibited.
What is the hamster study that shows the importance of endogenous pacemakers in circadian rhythms?
One study bread hamsters so that they had circadian rhythms of 20 hours rather than 24. the SCN neurons from these hamsters were transported into the brains of normal hamsters who also displayed the same abnormal circadian rhythm. This suggests that the SCN (endogenous pacemaker) plays a huge role in biological circadian rhythms.
