Ultradian and infradian rhythms Flashcards
How long do infradian rhythms last and give 2 examples.
Longer than 24 hours. Menstural cycle. Seasonal affective disorder (SAD).
Roughly how long is the female human menstrual cycle?
28 days.
What causes ovulation? (ovary develops & releases an egg)
Rising oestrogen levels.
What helps line the womb for pregnancy?
Progesterone.
What happens if pregnancy does not occur?
Egg absorbed into body and womb lining sheds - menstrual flow.
Outline research into the impact of exogenous zeitgebers on menstrual cycles.
29 women with irregular periods. Pheromones from armpits taken at different stages of cycles. After cleansing, rubbed on upper lips of other Ps. 68% of Ps cycle changed to get closer to “odour donor :/”. Suggests menstrual cycle can be influenced by exo zeits e.g cycles of other women.
What type of disorder is Seasonal Affective Disorder?
Depressive order with a seasonal pattern.
What is thought to cause SAD?
Melatonin secreted at night and stops in daylight. Winter - lack of light in morning - more melatonin produced. Reduced serotonin production in brain - links to onset of depressive symptoms.
How long to ultradian rhythms last and give an example.
Less than 24 hours. Sleep cycles.
How long does a complete sleep cycle of 5 stages last?
90 mins.
How can different stages of sleep be characterised and measured?
Different brainwave activity measured by an EEG.
What characterises stage 1 of the sleep cycle?
NREM. Light sleep. Slowed muscle activity (occasional twitching). Short stage.
What characterises stage 2?
NREM. Slowed breathing and heart rate. Slightly decreased body temp. Longest stage.
What characterises stage 3?
NREM. Deep sleep. Brain generates slow delta waves. Short stage.
What characterises stage 4?
NREM. Very deep sleep. Rhythmic breathing. Limited muscle activity. Delta waves. Medium-short stage.
What characterises stage 5?
REM - Rapid eye movement. Fast brainwaves (like awake). Dreaming. Relaxed muscles but increased heart rate. Rapid & shallow breathing. Medium-long stage.
(AO3) Explain methodological limitations of research into menstrual cycles.
Many factors impact menstrual cycle: stress, diet, exercise. Extraneous variables - changes in patterns may be due to chance. Small samples (generalisability). Relies on self-report. Study lacks validity.
(AO3) Explain a strength of research into infradian rhythms.
Developments of treatments for SAD. Phototherapy: lightbox stimulates strong light in morning and evening resets melatonin levels. Relieves symptoms in 60% of sufferers (placebo effect applies here).
(AO3) Outline a limitation of theories of sleep cycles.
Big individual differences in sleep patterns. Environmental influences such as room temp impacts patterns. But when measured in controlled lab, time taken to fall asleep and time of each stage varied between Ps. Suggests patterns are flexible and maybe influenced by bio / genetic factors.
(AO3) Outline research evidence for stages of sleep (include researcher names).
Dement and Kleitman. Sleep patterns of 9 adults using EEGs. Found distinct wave patterns, especially in REM. REM activity highly correlated with experiences of dreaming.
