biopsych - y13 - infradian and ultradian rhythms

Question 1

what are infradian rhythms? examples?

Answer 1

biological rhythms which takes more than a day to complete (menstruation) (seasonal depression)

Question 2

what are ultradian rhythms?

Answer 2

a biological rhythm which occurs many times within a 24 hour period, such as the stages of sleep.

Question 3

what does ICU (i see u) stand for?

Answer 3

Infradian (top is longest)
cicradian (middle is second longest)
ultradian) (shortest)

Question 4

what happens during the menstrual cycle (infradian)

Answer 4

-during each cycle, rising levels of oestrogen cause the ovary to develop and release an egg (ovulation).
-after ovulation, progesterone helps the womb lining grow thicker in preparation for pregnancy
-if pregnancy does not occur, the egg is absorbed into the body and the lining is shed for menstrual flow.

Question 5

is the menstrual cycle an endogenous system or exogenous?

Answer 5

endogenous but it may be influenced by exogenous factors.

Question 6

Russel et al (1980)

Answer 6

-found that the menstrual cycle can be synchronised by exogenous cues, which explains the phenomenon that women who live together often have synchronised cycles.
-to demonstrate this, they used volunteer participants who did not live together, and transferred sweat from the upper lips of the participants to each other, with the results that their cycles quickly became synchronised.
-they hypothesised that sweat must contain a pheromone, or chemical messenger, that resets the menstrual cycle.

Question 7

Stern and McClintock (1998)

Answer 7

-found similar results (russel) when they studied 29 women with a history of irregular periods
-pheromone samples were gathered from 9 of them during different point in their cycle (from a cotton pad placed in the armpit).
-the pads were treated with alcohol and frozen to be rubbed on the upper lip of the other participants
-found that 68% of the women experienced changes to their cycle which brought them closer to the cycle of their ‘odour donor’
-nature v nurture.

Question 8

what is seasonal affective disorder (SAD)

Answer 8

-an infradian rhythm which lasts about a year.
-could also be classed as a circadian rhythm as SAD may be due to the disruption of the sleep/wake cycle which may be attributed to prolonged periods of darkness during winter.
-involves feeling depressed in winter months but a better mood in summer months.

Question 9

SAD and melatonin? how do they link?

Answer 9

-during the night, the pineal gland secretes melatonin until dawn when light increases
-as there is a lack of light in the morning during winter, the secretion of melatonin continues for longer which may have an effect on the production of serotonin
-which has been liked to the onset of depression.

Question 10

what type of biological rhythm is the sleep cycle?

Answer 10

ultradian.

Question 11

how many stages of sleep are there and what is the last stage called?

Answer 11

5. REM sleep.

Question 12

how long does each stage of sleep last?

Answer 12

90 minutes.

Question 13

what happens during stages 1-2 of sleep?

Answer 13

-a light sleep where a person may be easily waken.
-in stage 1, brain waves are high frequency and short amplitude (alpha waves)
in stage 2, the alpha waves continue but there are occasional random changed in pattern called sleep spindles.

Question 14

what happens during stages 3-4 of sleep?

Answer 14

-known as a deep sleep.
-the brains waves are delta waves with lower frequency and higher amplitude and it is now difficult to wake someone up.

Question 15

what happens during stage 5 of sleep (REM) ?

Answer 15

-the body is paralysed yet brain activity closely resembles that of an awake brain
-during this time, the brain produces theta waves and the eyes occasionally move around.
-dreams are mostly experienced in REM sleep but may also occur during deep sleep.

Question 16

what happens at the end of a singular sleep cycle?

Answer 16

after REM sleep, there is a partial awakening, so we can then restart the sleep cycle.

Question 17

at the end of a sleep cycle (90 mins) what happens?

Answer 17

the cycle will then restart, and each stage becomes periodically longer.

Question 18

what did Kleitmann (1969) suggest?

Answer 18

a Basic-Activity Cycle which is a 90-minute cycle characterised by periods of alertness followed by physical fatigue, which occurs during the day where people find it difficult to concentrate for more than 90 minutes without having a break.

Question 19

Ericsson et al (1993)

Answer 19

-found that the best violinists tended to practice for three sessions in a day, with a break between each, and the sessions lasting no more than 90 minutes.

Question 20

what type of rhythm is BRAC?

Answer 20

ultradian.

Question 21

evaluation of the menstrual cycle?

Answer 21

-menstrual synchrony is thought to have an evolutionary basis
-for our ancestors, it may have been an advantage to menstruate at the same time, and therefore fall pregnant at the same time so that newly borns could be cared for collectively, having a better chance at survival.

Question 22

Schank (2004) argument against menstrual cycles evolutionary basis

Answer 22

-argues against this saying that if there were too many females sharing a cycle, this would produce competition for the highest quality males, which lowers the fitness of a potential offspring.
-therefore, the avoidance of cycling together would be the most adaptive strategy, and therefore naturally selected.

Question 23

how may the synchronisation studies be flawed?

Answer 23

-studies such as McClintocks may have had confounding variables such as stress, diet changes, exercise - all of which have an effect on menstrual cycles.
-therefore, synchronisation patterns may have occurred by chance
-the samples are also small and rely on self-reports about cycles.

Question 24

other evidence against menstrual cycles?

Answer 24

Trevathan et al (1993) have not found supporting evidence of menstrual synchrony in all female samples.

Question 25

evaluation of the sleep cycle?

Answer 25

-Dement and Kleitman (1957) monitored the sleep patterns of 9 participants in a sleep lab where caffeine and alcohol were controlled.
-their brain wave patterns were observed with an EEG. REM activity was highly correlated with dreaming, brain activity varied with how vivid the dreams were.
-participants woken up during dreaming and reported very accurate recall of the dream, suggesting that REM is an important part of the ultradian sleep cycle.

Question 26

what is one issue with Dement and Kleitmans study of the sleep cycle?

Answer 26

participants were in a very different environment from home, EEG equipment may be uncomfortable, the surroundings may not be similar as they are at home.

Question 27

slow wave sleep evaluation?

Answer 27

we have learned a lot about sleep. (slow wave sleep)
-it reduces with age. growth hormone is mostly produced during slow wave sleep therefore, this becomes deficient for older people.

Question 28

slow wave sleep evaluation study Eve van Cauter et al (2000)

Answer 28

the resulting deficit may explain various impairments in old age such as reduced alertness.
-in order to increase SWS, relaxation and medication may be used
-this suggests that knowledge of ultradian rhythms has practical value.

Question 29

practical application?

Answer 29

-phototherapy is a treatment used for SAD where a light box stimulates very strong light in the morning and evening, which is thought to rest melatonin levels.
- up to 60% of symptoms may be relieved i sufferers (Eastman et al 1998)
-studies show this helps reduce the effects of SAD in about 80% of people (Samassi 2014) it is preferred over drug therapy to treat SAD as it is regarded as more safe.