Ultradian and Infradian rhythms Flashcards
What are ultradian rhythms
Biological cycles which span less than one day
What are Infradian rhythms
Biological cycles which span more than one day
What is an example of an ultradian rhythm?
The Sleep Stages
How long is a sleep cycle
90-100 mins
What do EEGs show happens during sleep
As a person enters deep sleep their brainwaves slow down along with breathing and heartrate. During the fifth stage (REM sleep) the EEG pattern resembles that of an awake person
What is the sleep cycle referred to as
The Basic Rest Activity Cycle, or BRAC.
What are the 5 stages of sleep
-Stage 1 - 4-5% - light sleep - muscle activity slows, occassional twitching
-Stage 2 - 45-55% - Breathing pattern and heart rate slow down, slight decrease in body temp
-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% - REM - Brainwaves speed up and dreaming occurs. Muscles relax and heart rate increases. Breathing rapid and shallow
Who came up with the Basic Rest Activity Cycle and what did they suggest
Kleitman suggested that the BRAC cycle continues during the day, moving through stages of alertness to physiological fatigue approx every 90 mins. Research suggests the mind can focus for around 90 mins, and towards the end of this the body begins to run out of resources. Kleitman suggests that the existence of things like the 10:30 am coffee break prove this is going on
What is the main infradian rhythm
The menstrual cycle
Explain the stages of the menstrual cycle
The menstrual cycle lasts 28 days, with the cycle regulated by hormones, with these either promoting ovulation or prepping the uterus for fertilisation. Ovulation occurs halfway through the cycle, when oestrogen levels peak, and ussually lasts 16 to 32 hours. After this progesterone levels increase in preperation for possible implantation of an embryo in the uterus
What is a second infaradian rhythm
Seasonal Depression, with research suggesting that seasonal variation can cause some people to become severely depressed during the winter months (seasonal affective disorder).
What is an issue with the menstrual cycle being an infradian rhythm
It can be controlled by exogenous cues, not just endogenous systems. When several women of childbearing age live together their menstrual cycles tend to synchronise. In one study by Russell et al, daily samples of sweat were collected from one group of women and rubbed onto the upper lip of women in a seperate group. The groups were kept seperate but their menstrual cycles became synchronised with the odor donor. This suggests that the menstrual cycle can also be affected by pheremones, not just biological rhythms.
Who made women bluetooth synchronise their menstrual cycles
Russell et al
Are lunar rhythms an infradian rhythm
There is no empirical evidence to support the belief that lunar rhythms do anything, but belief in them remains strong. It isn’t even just druids or werewolves who believe this, with midewives still believing that more young babes are born on full moons and mental health professionals showing a belief that the full moon can alter behaviour, as revealed by Vance. Despite complete lack for this causal relationship the belief in this infradian rhythm is still popular
Who showed that psychology professionals can still believe in werewolf syndrome
Vance showed that many mental health professionals held a belief that the full moon can alter behaviour
Where has research support for the BRAC cycle come from
Ericsson et al studied a group of elite violinists and found that practise sessions were usually limited to a duration of no more than 90 mins at a time, with practise systematically distributed throughout the day. They also found that violinists frequently napped to recover from practise, with the best violinists napping more than their teachers. This is consistent with Kleitman’s predictions of BRAC.
What does BRAC mean
Basic Rest Activity Cycle
Who studied sleepy violinists
Ericsson
What are some individual differences in sleep stages (not duffy)
Differences in sleep patters are usually attributed to non-biological factors, but a study by Tucker et al suggests that these differences are in large part biologically determined and may even be genetic. Particpants were studied over 11 days in a strict lab environment, and were assessed for sleep duration, time to fall asleep and amount of time spent in each sleep stage. They found large individual differences in each of these characteristics consistently across the 8 nights Individual differences were particularly significant in deep sleep, and as conditions were so strictly controlled these must have been biologically determined
Who studied people sleeping in a lab
Tucker et al
