Biological Rhythms - BIOPSYCHOLOGY Flashcards
Biological Rhythms
(Circadian rhythms)
All living organisms have them
Changes in body processes across a time period
2 Example of Circadian rhythms
+ describe the less important one
-rhythms lasting 24 hours
-sleep/wake cycle
-Temperature
Highest at 6pm
Helps coordinate heart rate, digestion and hormones
High temperature = improved cognition
Endo: Suprachiasmatic nucleus
-Nerve fibres connected to eyes cross over in area called optic chiasm (located in hypothalamus)
-SCN lies just above this and recieves info of light directly from here
- Continues even when our eyes are closed, enabling biological clock to ajust to light patterns when we are asleep
(passes light info onto the pineal gland
(-The pineal gland then increases production of Melatonin (when there is little light) - a chemical that induces sleep))
Endo: pineal glans and Melatonin
SCN passes info on day length and light to Pineal gland
During night, pineal gland produces Melatonin
Melatonin makes sleep more ‘inviting’ (induces sleep)
Exo: Light
Can reset SCN
Indirectly Inhibits production of Melatonin present
(also indirectly influences hormone secretion and blood circulation)
Exo: social cues
Schedules set by parents to entrain babies e.g: eating, sleeping
-babies have random cycles until 16 months old when they are entrained
Infradian rhythm
Frequency of less than 1 in 24 hrs
The menstrual cycle
Governed by monthly changes hormones.
Cycle refers to first day of woman’s period when wall lining is shed to day before her next period.
Cycle takes around 28 days .
Is the Menstrual cycle an endogenous system
Yes, by oestrogen and other hormones. although some psychologist argues that it is effected by exogenous zietgebers such as other women’s cycles (pheromones)
Seasonal affective disorder
Depressive disorder. Has seasonal pattern of onset.
Symptoms are persistent low moods
During night, pineal gland secretes Melatonin until daylight shows. During winter there is a lack of light. This is thought to affect the production of seratonin- a chemical linked to depression
Ultradian rhythms
Frequency of more than 1 in 24 hrs
Sleep cycle
5 distinct stages
-occour within around 90 minutes
-each stage characterised via different levels of brainwave activity measured using an EEG
What are the 5 stages of The sleep cycle
1, 2, light sleep
3, 4, deep sleep
5:REM
Stages 1 and 2 of sleep cycle
-light sleep, person easily woken
-brainwaves slower and more rhythmic(alpha waves)
Becoming even slower as sleep becomes deeper (Theta waves)
Stages 3 and 4 of sleep cycle
-delta waves
-even slower, greater amplitude
-hard to wake someone up
Stage 5 of sleep cycle
REM sleep
-body is paralysed
-brain activity speeds up to that of an awake brain
-linked to dreaming
Who re-surfaced from a cave in mid-September 1962 believing it to be mid-August?
Michael Siffre
Who found that participants living in a WW2 bunker for 4 weeks had a circadian rhythm between 24-25 hours?
Aschoff and Wever
Who sped up a clock for a 22 hour day and found participants could not cope with the change?
Folkard et al
Who found that they could alter women’s menstrual cycles by rubbing the pheromones of another woman onto their top lip?
Stern + McClintock
Who found that they could alter sleep patterns of participants by shining lights on the backs of their knees?
Campbell + Murphy
Folkard (1977)
temperature study
aims + procedure
- Was interested in cognitive ability and its association with body temperature - Read children stories at 3pm and 9am
Folkard (1977)
temperature study
Findings
Children were much more able to recall and understand information from stories read to them at 3pm
Aims of Siffre’s study
to study the effects on Endogenous pacemakers on his 24 hr sleep cycle
procedure of Siffre’s study
the effects on his rhythms - In 1962 he spent 2 months in a cave - In 1972 he spent 6 months in a cave
No light
Findings + of Siffre’s study
in 1962 he resurfaced after 2 months in a cave believing it to be mid August when it was mid September
He always woke and slept in a regular cycle
conclusions of Siffre’s study
Endogenous pacemakers do govern the sleep wake cycle
Aschoff + Wever study
procedure
Convinced a group of participants to spend 4 weeks in a WWII bunker deprived of natural light
Aschoff + Wever findings
All but one (whose sleep/wake cycle was 29 hours) displayed a circadian rhythm between 24-25 hours rather than 24 hours exactly
