Infradian and ultradian rhythms -A-Level Psychology

Infradian and ultradian rhythms

Infradian rhythms:

The female menstrual cycle is governed by monthly changes in hormone levels which regulate ovulation.Typical cycle takes 28 days to complete.

Research study:Stern and McClintock

Although the menstrual cycle is an endogenous system,evidence suggests that it may be influenced by exogenous factors such as the cycles of other women.They studied how menstrual cycles may synchronise as a result of the influence of female pheromones.Samples of pheromones from the armpits of 9/29 women were collected at different stages of their menstrual cycles.The cotton pads with the pheromones were then rubbed on the upper lip of the other pps. Findings showed that 68% of women experienced changes to their cycle which brought  them closer to the cycle of their ‘odour donor’.

Seasonal affective disorder:

-is a depressive disorder which has seasonal patterns

-circannual rhythm as it is a yearly cycle

-symptoms triggered during the winter months

-during the night the pineal gland secretes melatonin until dawn when there is an increase in light.In the winter,the lack of light means the secretion process continues for longer which is thought to have an effect on the production of serotonin in the brain.

Ultradian rhythms:

The sleep cycle has five distinct stages around 90 minutes,the cycle continues throughout the night.Each of these stages is characterised by a different level of brainwave activity which can be monitored with an EEG.

Stages 1 and 2 (sleep escalator)-light sleep where the person may be easily woken.At the beginning of sleep ,brainwave patterns start to become slower and more rhythmic(alpha waves) which then become slower as sleep progresses(theta waves)

Stages 3 and 4-involve delta waves which are slower and have a greater amplitude than earlier wave patterns.This is deep sleep and it is difficult to wake someone up at this point.

Stage 5(REM sleep)-the body is paralysed yet brain activity speeds up to resemble the awake brain.REM stands for rapid eye movement to denote the fast activity of the eyes under the eyelids .Dreaming occurs.


Evolutionary basis of the menstrual cycle-it may have been advantageous for females to menstruate together and fall pregnant at the same time so that new born could be cared for collectively within the social group to increase the chances of the offsprings survival.Some argue this would produce competition so the avoidance of synchrony may have been the most adaptive evolutionary strategy and therefore naturally selected.

Evidence for REM sleep-Dement and Kleitman studied  9 pp’s sleep patterns in a sleep lab. Brainwave activity was recorded on an EEG and the researchers controlled for the effects of caffeine and alcohol.REM activity during sleep was highly correlated with the experience of dreaming,brain wave activity varied according to how vivid the dreams were.Pp’s woken during this time reported having a very accurate recall of their dreams.The sample size was criticised.

→ What are infradian rhythms?

Infradian rhythms are biological rhythms that occur over a period longer than 24 hours. Examples of infradian rhythms include the menstrual cycle in females, the hibernation cycle in bears, and the migration patterns of birds.

→ What are ultradian rhythms?

Ultradian rhythms are biological rhythms that occur over a period shorter than 24 hours. Examples of ultradian rhythms include the sleep cycle, the feeding cycle, and the hormonal cycles that regulate digestion and metabolism.

→ How do infradian and ultradian rhythms differ?

Infradian rhythms occur over a longer period than 24 hours, while ultradian rhythms occur over a shorter period than 24 hours. Infradian rhythms are typically associated with long-term biological processes such as reproduction and hibernation, while ultradian rhythms are associated with shorter-term processes such as sleep and feeding.

→ What are some examples of infradian rhythms in humans?

The menstrual cycle in females is an example of an infradian rhythm in humans. Other examples include the seasonal affective disorder (SAD), which is a type of depression that occurs during the winter months, and the annual cycles of weight gain and loss.

→ What are some examples of ultradian rhythms in humans?

The sleep cycle is an example of an ultradian rhythm in humans. Other examples include the feeding cycle, which is regulated by hormones such as ghrelin and leptin, and the hormonal cycles that regulate digestion and metabolism.

→ How do infradian and ultradian rhythms affect our behavior?

Infradian rhythms can affect our behavior by influencing our mood, energy levels, and cognitive functioning. Ultradian rhythms can affect our behavior by regulating our sleep, appetite, and other bodily functions.

→ Can infradian and ultradian rhythms be disrupted?

Yes, both infradian and ultradian rhythms can be disrupted by various factors such as stress, environmental changes, and illness. Disruptions to these rhythms can have negative effects on our physical and mental health.

→ How can we manage disruptions to our infradian and ultradian rhythms?

To manage disruptions to our infradian and ultradian rhythms, we can take steps such as maintaining a regular sleep schedule, practicing stress-management techniques, and seeking medical treatment for any underlying health conditions.

→ How are infradian and ultradian rhythms relevant to A-Level Psychology?

Infradian and ultradian rhythms are important topics in A-Level Psychology because they help us understand how biological processes influence our behavior and mental health. Studying these rhythms can also help us develop strategies for managing disruptions to our sleep, appetite, and other bodily functions.

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