Discuss research into infradian rhythms. (16 marks)
Outline:
Biological rhythm, longer than 24 hours, e.g. menstrual cycle (28 days)
Oestrogen and progesterone endogenous pacemakers
Oestrogen development and release of egg (ovulation), progesterone thickens uterus lining
Womb lining breaks down if no fertilisation
McClintock, pheromones exogenous zeitgebers
Gained pheromones from different stages, rubbed on upper lips
68% changes in cycle
SAD circannual rhythm
Symptoms – persistently low mood, anhedonia – triggered in winter months
Increased melatonin from pineal gland associated with less daylight affects serotonin
production, causing onset of depressive symptoms
Outline:
P: research with similar results to McClintock’s
E: Russell’s replication found same conclusions, Mora and Cabrera infradian and pheromones in
rats
C: small samples, not generalisable to women universally
A: stress, diet affect cycle, confounding variables
A: explains why Trevathan replication failed to find synchrony
L: issues with reliability and internal validity, scientific nature of claims is questionable
P: McClintock’s suggestion that menstrual synchrony has evolutionary advantage disputed
E: advantageous to menstruate together, care for new-borns collectively, survival
C: Schank, produces competition for best males, limits potential of offspring
A: raising new-borns collectively, extra pressure on resources such as food/water
L: limited understanding of why pheromones are zeitgebers
P: practical applications to treating SAD
E: Eastman, phototherapy – lightbox that stimulates strong light in morning and evening to reset
melatonin – relieves symptoms in 60%
C: negative ion generate (no physiological effect), relieved in 30%
L: placebo effect makes it hard to analyse effectiveness, however beneficial for some users
Outline:
Biological rhythm, longer than 24 hours, e.g. menstrual cycle (28 days)
Oestrogen and progesterone endogenous pacemakers
Oestrogen development and release of egg (ovulation), progesterone thickens uterus lining
Womb lining breaks down if no fertilisation
McClintock, pheromones exogenous zeitgebers
Gained pheromones from different stages, rubbed on upper lips
68% changes in cycle
SAD circannual rhythm
Symptoms – persistently low mood, anhedonia – triggered in winter months
Increased melatonin from pineal gland associated with less daylight affects serotonin
production, causing onset of depressive symptoms
Outline:
P: research with similar results to McClintock’s
E: Russell’s replication found same conclusions, Mora and Cabrera infradian and pheromones in
rats
C: small samples, not generalisable to women universally
A: stress, diet affect cycle, confounding variables
A: explains why Trevathan replication failed to find synchrony
L: issues with reliability and internal validity, scientific nature of claims is questionable
P: McClintock’s suggestion that menstrual synchrony has evolutionary advantage disputed
E: advantageous to menstruate together, care for new-borns collectively, survival
C: Schank, produces competition for best males, limits potential of offspring
A: raising new-borns collectively, extra pressure on resources such as food/water
L: limited understanding of why pheromones are zeitgebers
P: practical applications to treating SAD
E: Eastman, phototherapy – lightbox that stimulates strong light in morning and evening to reset
melatonin – relieves symptoms in 60%
C: negative ion generate (no physiological effect), relieved in 30%
L: placebo effect makes it hard to analyse effectiveness, however beneficial for some users
