biological rhythms: infradian rhythms Flashcards
(16 cards)
What is an infradian rhythm?
A biological rhythm with a cycle longer than 24 hours, such as the menstrual cycle or seasonal affective disorder.
What is the menstrual cycle?
A monthly cycle in women governed by hormonal changes, regulating ovulation and menstruation, typically lasting about 28 days.
What hormones are involved in the menstrual cycle?
Oestrogen (causes egg development and release) and progesterone (prepares womb lining for pregnancy).
What happens if pregnancy does not occur after ovulation?
The egg is absorbed, the womb lining breaks down, and menstruation occurs.
What is meant by synchronising the menstrual cycle?
The idea that menstrual cycles of women living together may become synchronized due to external factors like pheromones.
Describe the Stern and McClintock study on menstrual synchrony.
Pads with pheromones from women at different menstrual stages were applied to other women, resulting in cycle changes closer to the ‘odour donor’.
What are exogenous factors in the context of the menstrual cycle?
External influences, such as pheromones, that may affect the timing of biological rhythms like the menstrual cycle.
What is a strength of menstrual synchrony research from an evolutionary perspective?
It may have been adaptive for women to menstruate and become pregnant together, enabling shared childcare and access to breast milk.
What is a methodological limitation of menstrual synchrony studies?
Confounding variables (e.g. stress, diet, exercise) may influence results, making findings difficult to replicate.
What is Seasonal Affective Disorder (SAD)?
A depressive disorder with a seasonal pattern, typically occurring in winter when daylight hours are shorter.
How is SAD classified in terms of biological rhythms?
It is a type of infradian rhythm (annual cycle) but can also be seen as a circadian rhythm disruption due to changes in the sleep/wake cycle.
What hormone is implicated in SAD?
Melatonin, which is secreted by the pineal gland for longer periods during winter, potentially reducing serotonin and causing depressive symptoms.
What is a common treatment for SAD and how effective is it?
Light therapy, which simulates strong sunlight and helps about 80% of sufferers, is considered safe and preferred over antidepressants.
What is a potential side effect of light therapy for SAD?
It can cause headaches and eye strain.
How does the relapse rate for SAD compare between light therapy and CBT?
Relapse rate is 46% for light therapy versus 27% for CBT, according to Rohan et al.
What chemical is linked to depressive symptoms in SAD?
Serotonin, which is reduced when melatonin secretion is increased.
