Biopsychology - Infradian and Ultradian Rhythms Flashcards
What is the menstrual cycle and how is it governed?
The menstrual cycle is an example of an infradian rhythm regulated by monthly hormonal changes. The cycle lasts approximately 28 days, beginning with the first day of menstruation. Rising oestrogen levels cause the ovary to release an egg, and progesterone helps thicken the womb lining for pregnancy. If fertilization does not occur, the lining is shed during menstruation.
How might the menstrual cycle be influenced by external factors?
Though endogenous, the menstrual cycle can be influenced by exogenous factors like pheromones. McClintock (1998) studied 29 women with irregular periods and found that pheromones collected and applied to participants could synchronize cycles. For instance, 68% experienced changes aligning their cycle with the pheromone donor’s cycle.
What is Seasonal Affective Disorder (SAD) and what causes it?
SAD is a depressive disorder triggered by seasonal changes, classified in the DSM-5. It is linked to the prolonged secretion of melatonin during winter due to reduced daylight, which impacts serotonin production and disrupts the sleep/wake cycle. SAD is considered a circadian rhythm disorder.
What are ultradian rhythms, and how are they exemplified in the sleep cycle?
Ultradian rhythms occur more than once in 24 hours, with the sleep cycle being a prime example. The cycle involves five stages lasting around 90 minutes:
Stages 1 and 2: Light sleep where brain activity slows.
Stages 3 and 4: Deep sleep or slow wave sleep characterized by delta waves.
Stage 5: REM sleep with rapid brain activity resembling the awake brain, linked to dreaming.
What is one evaluation point about the evolutionary basis of the menstrual cycle?
The menstrual cycle’s synchronization may have evolutionary advantages, promoting group pregnancy and offspring survival. However, Schank (2004) criticized this, suggesting synchrony might lead to competition for mates and would not benefit reproductive success.
What is one evaluation point about methodological issues in menstrual cycle research?
Synchronization studies are criticized for confounding factors like diet, stress, and exercise. Self-reported data from participants may not be reliable, and McClintock’s findings could be due to chance, as replication attempts have failed.
What is one evaluation point about Seasonal Affective Disorder (SAD)?
A key treatment for SAD is phototherapy, which simulates natural light. It has been effective for up to 60% of sufferers (Eastman et al., 1998). However, studies with placebo controls show a similar effectiveness rate, raising doubts about phototherapy’s specificity.
What is one evaluation point about research into sleep stages?
Dement and Kleitman (1957) found high correlations between REM sleep and dreaming, with brainwave activity varying depending on the dream’s vividness. However, their small sample size limits generalizability.
