Infradian + Ultradian Rhythms

Question 1

What is an infradian rhythm?

Answer 1

A type of biological rhythm with frequency of less than one cycle in 24 hours, such as menstruation or seasonal affective disorder

Question 2

What is an ultraradian rhythm?

Answer 2

A type of biological rhythm with a frequency of more than one cycle in 24 hours, such as the stages of sleep

Question 3

Why is the menstrual cycle an infradian rhythm?

Answer 3

• It’s governed by monthly changes in hormone levels which regulate ovulation.
• The cycle refers to the time between type first day of a period when lining is shed to the day before her next period
• Oestrogen helps the ovary develop a egg and release while protestors helps womb lining grow thicker

Question 4

What did McClintock research?

Answer 4

• How menstrual cycle in an endogenous system but may be influenced by exogenous factors such as the cycles of other women.
• 29 women with history of irregular periods, samples of pheromones were gathered via a cotton pad in their armpit (8 hours)

-Rubbed on upper lip of other participants
- 68% experienced changes which brought them closer to the cycle of their odour donor

Question 5

What is SAD?

Answer 5

Seasonal affective disorder, a depressive disorder which has a seasonal pattern onset and is described and diagnosed as a mental disorder in DSM-5. As with other forms of depression the main symptoms is lo mood and lack of activity and interest in life. Infradian as a yearly rhythm could also be circadian as disruption of sleep/ wake in winter

Question 6

Why is melatonin essential in SAD?

Answer 6

• During the night the pineal gland secretes melatonin until light of dawn. During winter, the lack of light in thee morning means this i secreted longer meaning serotonin production lowers causing depressive systems.

Question 7

What are the stages of sleep

Answer 7

Each night the stages are characterised by different level of brain activity- EEG

Stages 1 + 2- Light sleep, easily woken alpha waves
Stages 3 + 4- This is known as deep sleep or slow wave sleep (SWS), the brain waves are delta waves with lower frequency and higher amplitude it is difficult to wake up sometimes.
Stages 5 (REM sleep)- The body is paralysed yet brain activity closely resembles an awake brain, brain produces theta waves and eyes occasionally move around (REM). Dreams often experienced but may occur in deep sleep

Question 8

Evaluation of infradian rhythm research?

Answer 8

• Menstrual synchrony research has an evolutionary basis, advantageous for women to menstruate together and become pregnant babies who lost mother would have access to breast milk. Synchronisation is an adaptive strategy.
• Methodological shortcomings, effect change to cycle stress, diet and exercise. Other studies failed to replicate menstrual synchrony studies are flawed

Question 9

What are the evaluations of ultradian rhythm research?

Answer 9

• Improved understanding into age related changes in see, SWS reduces with age. Cauter et al (2000) sleep deficit explain issues in old age, reduced alertness. Practical value, use to medicate
• One limitation of ultradian rhythm research is there’s a significant variation between people Tucker et al found large differences between participants in term of duration of sleep stage, biologically determined difficult to describe normal sleep