Biological rhythms: infradian rhythms

Question 1

infradian rhythm definition

Answer 1

type of biological rhythm with a frequency of less than one cycle in 24 hours (takes more than a day) such as menstruation and seasonal affective disorder

Question 2

type of brainwave in stage 1

Answer 2

alpha waves

Question 3

type of brainwave in stage 2

Answer 3

alpha and sleep spindles

Question 4

type of brainwave in stage 3 and 4

Answer 4

delta waves

Question 5

type of brainwave in stage 5 (REM sleep)

Answer 5

theta waves

Question 6

what type of biological rhythm is the menstrual cycle

Answer 6

infradian rhythm

Question 7

what is menstrual cycle governed by

Answer 7

monthly changes in hormone levels which regulate ovulation

Question 8

what does the menstrual cycle refer to

Answer 8

time between the first day of a period (when womb lining is shed) to the day before the next period

Question 9

how long does menstrual cycle take

Answer 9

typically 28 days (but form 24-35 days is considered normal)

Question 10

what happens during the menstrual cycle

Answer 10

rising levels of the hormone oestrogen causes the ovary to develop an egg and release it (ovulation). after ovulation the hormone progesterone helps the womb lining to grow thicker which causes the womb to be ready for pregnancy which is does not occur, the egg is absorbed into the body, the womb lining comes away and leaves the body (menstrual flow)

Question 11

is the menstrual cycle endogenous or exogenous

Answer 11

endogenous system but can be influenced by exogenous factors

Question 12

what are the exogenous factors that can effect the menstrual cycle

Answer 12

cycles of other women –> pheromones

Question 13

Stern and McClintock study

Answer 13

how menstrual cycles may synchronise as a result of the influence of pheromones

Question 14

when did Stern and McClintock research

Answer 14

1998

Question 15

Stern and McClintock sample

Answer 15

29 women with a history of irregular periods

Question 16

Stern and McClintock procedure

Answer 16

-29 women with history of irregular periods
-samples of pheromones were gathered from 9 women at different stages of the menstrual cycle, via cotton pads placed under their armpit
-pads were worn for at least 8 hours to endure that pheromones had been picked up
-pads were treated with alcohol and frozen
-pads were rubbed on the upper lip of the other 20 participants
-on day 1 pads from the start of the menstural cycle were applied to the 20 women, on day 2 they were given pads from day 2 etc..

Question 17

Stern and McClintock findings

Answer 17

68% of women experienced changes to their cycle which bought them closer to the cycle of their odour donor

Question 18

what is seasonal affective disorder (SAD)

Answer 18

depressive disorder which has a seasonal pattern of onset. categorised as a mental disorder in the DSM-5

Question 19

main symptoms of SAD

Answer 19

as with other forms of depression its symptoms are persistent low moods alongside a general lack of activity and interest in life

Question 20

what is SAD often referred to

Answer 20

winter blues as the symptoms are triggered during the winter months

Question 21

why is SAD in the winter months

Answer 21

number of daylight hours becomes shorter

Question 22

what type of infradian rhythm is SAD and why

Answer 22

circannual rhythm as is subject to a yearly cycle. can also be classed as a circadian rhythm as the experience of SAD may be due to disruption to sleep/wake cycle and this can be attributed to prolonged periods of daily darkness during winter

Question 23

what hormone have psychologists hypothesised is involved in SAD

Answer 23

melatonin

Question 24

how is melatonin involved in SAD

Answer 24

at night, the pineal gland recreated melatonin until dawn when there is an increase in light. during winter, the lack of light in the morning means melatonin is secreted for longer. this has a knock-on effect on the production of serotonin in the brain which has been linked to depressive symptoms

Question 25

strength of infradian rhythms - evolutionary basis

Answer 25

-menstrual synchrony research can be explained by natural selection
-synchronisation of the menstrual cycle such as observed by Stern and McClintock has some evolutionary value. for example, for distant ancestors it may have been advantageous to be pregnant at the same time. in a social group, babies who had lost their mothers during or after childbirth to have access to breast milk and improve their chance of survival –> suggests synchronisation is an adaptive strategy

Question 26

limitation of infradian rhythms - methodological limitations

Answer 26

-limitation of synchronisation studies is their methodological shortcomings
-many factors that may effect change to the menstrual cycle such as stress, change in diet, exercise. these may act as confounding variables which means that an supposed pattern of synchronisation is no more than would have been expected to occur by chance. this may explain why other studies (trevathan et al 1993) have failed to replicate findings–> suggets menstrual synchrony studies are flawed

Question 27

evaluation of infradian rhythms - real-world application

Answer 27

-one of the most effective treatments for SAD is light therapy, a box which stimulated very strong light to reset the body’s internal clock. studies show this helps reduce effects of SAD in about 80% of people (Sanassi 2014). light therapy is also preferred over antidepressants to treat SAD as is regarded as safe
-however, light therapy can produce headaches and eye strain. perhaps more tellingly, Rohan et al 2009 recorded a relapse rate of 36% over successive winters, completed to 27% in group with CBT