Ultradian and Infradian rhythms

Question 1

what are infradian rhythms

Answer 1

rhythms that have a duration of over 24 hours and may be weekly, monthly and anually

Question 2

What are ultradian rhythms

Answer 2

cycles that last less than 24 hours, such as the cycle of sleep stages of sleep stages that occur throughout the night.

Question 3

Explain the sleep stages

Answer 3

the ultradian rhythm found in human sleep follows a pattern of alternating REM (rapid eye movement) NREM (non-rapid eye movement) sleep which consists of stages one to four. This cycle repeats itself every 90-100 minutes throughout the night, with different stages having different durations

Question 4

Describe the sleep stages

Answer 4

Stage 1 4-5% light sleep. Muscle activity slows down. Occasional muscle twitching
Stage 2 - 45-55% Breathing pattern and heart rate slows. Slight decrease in temperature
Stage 3 4-6% deep sleep begins. Brain begins to generate slow delta waves.
Stage 4 12-15% very deep sleep. Rhythmic breathing. Limited muscle activity. Brain produces delta waves
Stage 5 20-25% rapid eye movement. Brainwaves speed up and dreaming occurs. Muscles relax and heart rate increases. Breathing is slow and shallow.

Question 5

Explore an infradian rhythm

Answer 5

menstrual cycle
the cycle is regulated by hormones which promote ovulation or stimulate the uterus for fertilisation

Question 6

What is the Basic activity rest cycle?

Answer 6

A 90 minute cycle found during the sleep of Kleitman suggested. He also suggested that this 90 minute ultradian cycle continues during the day
The only difference is that during the day rather than moving from stages of sleep, we move from a state of alertness to psychological fatigue every 90 minutes.

Question 7

Name a first evaluation point

Answer 7

There are individual differences in the sleep stages
These differences are usually attributed to differences in non-biological factors (sleep hygiene) However Tucker et al in 2007 suggested that these individual differences were biological
Participants were studied over 11 consecutive days and nights in a strictly controlled laboratory environment
The researchers assessed sleep duration, time to fall asleep and the amount of sleep in each stage of sleep
They found large individual differences in each characteristic which showed up consistently for 8 nights.
For deep sleep the individual differences were particularly significant

Question 8

Name a second evaluation point

Answer 8

There is research support for the BAAC
Ericsson et al in 2008 provided research support in a study of elite performers
They studied an elite group of violinists and found that among this group practice sessions were limited to a duration of no longer than 90 minutes at a time with practice systematically distributed throughout the day in these 90 minute segments
This supported Kleitman’s claim that fatigue was a characteristic of the BRAC cycle
Ericsson found that violinists napped to recover from practice with the best violinists napping more than the teachers

Question 9

Name a third evaluation point

Answer 9

The menstrual cycle is usually governed by an endogenous system however, exogenous cues can also be influential in this cycle.
When women of a childbearing age live together and do not take oral contraceptives their menstrual cycle tends to synchronise
In a study by Rusell et al in 1980 daily sweat samples were collected from one group of women, rubbed onto the upper lip of women in the second group
The groups were kept separate yet their menstrual cycle was still synchronised
This suggests that the synchrony of menstrual cycles can be due to phermones

Question 10

Name a fourth evaluation point

Answer 10

The menstrual cycle matches mate choice
Penton-Voak et al in 1999 suggests that human mate choices vary across the menstrual cycle
They found that women generally expressed a preference for a ‘slightly’ feminised male face when picking a partner for a long term relationship
However, when ovulating, they preferred a masculine face

Question 11

Name a final evaluation point

Answer 11

There is a belief in lunar rhythms
Despite empirical evidence, the belief in infradian rhythms based on the phases of the moon is still strong
Many midwives believe that more babies are born on a full moon than a new moon
Statistics show this is based on a subjective association (Arliss et al in 2005)
Likewise surveys of workers in mental health professions have shown a persistent belief that the moon can alter behaviour (Vance 1995)
Many studies have failed to show any consistent association between the moon and psychopathalogy
Foster and Roennenberg in 2008 have shown correlation between the phase of the moon and various aspects of human behaviour