biological rhythms

Question 1

3 biological rhythms and their duration

Answer 1

Infradian- longer than 24 hours

Circadian- 24 hours

Ultradian- less than 24 hours

Question 2

A01 of infradian rhythms

Answer 2

weekly monthly annually

1) female menstrual cycle regulated by hormones
–> ovulation occurs when oestrogen levels are the highest- 16-32 hours
–> after ovulation, progesterone levels increase in case of fertilisation
28 days (23-36)

2) SAD- yearly cycle
–> longer period of melatonin secretion- depression in winter
–> melatonin secreted by pineal gland at night- longer nights in winter

Question 3

AO3 of infradian rhythms

Answer 3

Reinberg (1967)
examined a woman who spent 3 months in a cave with a small lamp to provide light.
–> menstrual cycle shortened from 28–>25.7 days
–> menstrual cycle governed by exogenous zeitgebers (lack of light)- external factor

       **Russel et al (1980)** female menstrual cycles become **synchronised** through odour exposure.  --> rubbed sweat sample onto upper lip  --> MC affected by pheromones (exogenous zeitgeber)

Question 4

A01 of circadian rhythms

Answer 4

24 hour rhythm reset by levels of light

1) sleep-wake cycle
endogenous pacemaker/ internal body clock of suprachiasmatic nucleus (SCN)

regulates sleep-waking patterns

by sending messages to pineal gland to release melatonin

2) body temp
lowest in morning (36 °C)
highest early evening (38°C)

sleep occurs when temp drops and rises to provide alertness in the morning

Question 5

A03 of circadian rhythms

Answer 5

Siffre
+6 months in a cave without external cures- 25 hrs

believed that he experienced fewer days than everyone else
–>exogenous zeitgebers regulate internal body clocks

Duffy et al 2001
morning people go bed early
evening people go bed later

innate individual differences

Question 6

A01 ultradian rhythms

Answer 6

human sleep patterns
5 stages of sleep occur in a 90 minute cycle
1+2) Alpha waves and spindles
light sleep
3+4) Deep sleep, delta waves
deep sleep
5) REM sleep, theta waves
dream sleep

Question 7

ultradian rhythm A03

Answer 7

Gardener
-remained awake for 264 hours
-slept for 15 hours over several nights, recovered 25% of his lost sleep
–> large degree of flexibility of diff stages in sleep cycle

Tucker
found significant differences of durations of stages 3 + 4
–> innate individual differences