Biological Rhythms: Ultradian and Infradian. Flashcards
A2 content
What is an infradian rhythm?
A type of biological rhythm with a frequency of less than one cycle in 24 hours (occurs over a longer period)
What is a ultradian rhythm?
A type of biological rhythm with a frequency of more than one cycle in 24 hours (occurs more than once in 24 hours).
Name an example of an infradian rhythm?
Menstrual Cycle/Seasonal Affective Disorder.
Name an example of an ultradian rhythm?
Stages of sleep.
Why is the menstrual cycle an example of an infradian rhythm?
Governed by monthly changes in hormone levels which regulate ovulation.
Cycle refers to time between first day of woman’s period, when womb lining is shed and the day before her next period.
How long is a typical menstrual cycle?
28 days (can vary 24-35 though).
How do endogenous factors and exogenous factors affect the menstrual cycle?
Endogenous = oestrogen/progesterone.
Exogenous= female pheromones, diet, stress, exercise.
What did Kathleen Stern and Martha McClintock (1998) study show?
Demonstrated how menstrual cycles may synchronise as a result of the influence of female pheromones.
29 women, history of irregular periods. Cotton pad under armpit 8 hours - frozen treated with alcohol.
68% women experienced changes to cycle.
What is SAD?
A depressive disorder which has a seasonal pattern of onset and is described as a mental disorder in DSM 5.
What are the symptoms of SAD?
Persistent low mood, general lack of activity and interest in life.
How is SAD linked to biological rhythms?
Circannual rhythm (yearly) but also circadian (affects sleep wake cycle).
Hormone melatonin implicated in cause of sad- lack of light means secretion process continues for longer. Thought to have knock on effect on production of serotonin.
What is an effective treatment for SAD?
Light therapy. (Sanassi, 2014) studies have shown light boxes may reduce symptoms of SAD in 80% of people.
Explain how the sleep stages work (ultradian).
Stage 1/2 light sleep (alpha waves) - sleep spindles.
Stage 3 and 4 (deep sleep/slow wave sleep) delta waves.
Stage 5 (REM SLEEP) theta waves, dreams occur etc.
Why is it good to look at the stages of sleep in lab settings?
Control for extraneous variables.
Why has research into the sleep stages and ultradian rhythms had practical applications?
Allowed us to understand how sleep changes as you age and how this implicates things such as growth hormones.
