Infradian and Ultradian Rhythms Flashcards
Infradian
A type of biological rhythms with a frequency of less than one cycle in 24 hrs: menstrual cycle, SAD and lack of melatonin during winter months
Ultradian
A type of biological rhythm with a frequency of more than one cycle in 24 hrs
BRAC: Basic Rest and Activity Cycle, Sleep Stages
What is the approximate regularity of the menstrual cycle
28 days
Why is menstrual cycle infradian cycle
Infradian rhythms last longer than 24 hours and can be weekly, monthly or annually. A monthly infradian rhythm is the female menstrual cycle, which is regulated by hormones that either promote ovulation or stimulate the uterus for fertilisation
now avani explain the cycle w hormones n shi
i aint bothered to type it all out
What exogenous factors can change the menstrual cycle of women not on hormonal contraception
Diet and stress
Other researchers have failed to replicate McClintock’s findings. Why this bad
Low validity
No support
Seasonal affective disorder
SAD
Annual rhythms are related to seasons, in particular migration in response to lower body temperatures
This may also affect human behaviour, as research suggests seasonal variations in mood in particular for women, with some people becoming severely depressed in the winter months
SAD: a depressive disorder which has a seasonal pattern of onset (DSM-5)
Main symptoms = persistent low mood alongside a general lack of activity and interest in life
Winter = increase in heart attacks
What is practical application of SAD
Lack of sunlight creates depression in some people, phototherapy has been found has been found to be an effective treatment
Eastman randomly assigned 96 patients with winter SAD to one of 3 bright light treatments that are about 10-20x brighter than ordinary indoor lights
Patients either got an hour an a half of bright light in the morning, an hour and a half in the evening, or a morning placebo of 2 deactivated negative-ion generators
After 3 weeks = significantly more people in the morning light treatment group than in the placebo group, showed significantly more people in the morning light treatment group than in the placebo group, showed significantly more complete or near-complete remission if their symptoms.
Stage 1 - sleep cycle
Non-REM sleep, transition from wakefulness to sleep. Last less than 10 minutes and is marked by slowing heartbeat, breathing and eye movements as well as relaxing of muscles, light sleep
Alpha and theta waves
Can get hypnagogic hallucinations (e.g. tetrys) or hypnic jerks (falling)
Stage 2 ultradian sleep cycle
Light sleep, person may be easily woken
Theta waves
Stage 3 - ultradian sleep cycle
Slower still and have a greater amplitude than earlier wave patterns
Deep sleep or slow wave sleep and is difficult to rouse someone at this point
Delta waves
REM sleep (stage 4)
Body is paralysed yet brain activity speeds up significantly in a manner that resembles the awake brain
REM stands for rapid eye movement to denote the fast, jerky activity of the eyes under the eyelids at the point. Research has suggested that REM activity during sleep is highly correlated with the experience of dreaming
Delta waves
Example of endogenous pacemaker influencing sleep/wake cycle
SCN
Lies in the hypothalamus
Example of an exogenous zeitgeber influecning sleep/wake cycle
Light
This is key zeitgeber (time giver) and social cues
