1/15
Looks like no tags are added yet.
Name | Mastery | Learn | Test | Matching | Spaced |
---|
No study sessions yet.
what are biological rhythms
cyclical patterns of changes
what are the 3 types of biological rhythms
ultradian, circadian, infradian
ultradian rhythm
biological process that repeats more frequently than once every 24hrs (minutes/hours), e.g. stages of sleep
circadian rhythm
biological process that repeats approximately every 24hrs, e.g. sleep/wake cycle, core body temp
infradian rhythm
biological process that repeats less frequently than once every 24 hrs (weeks/months), e.g. menstrual cycle
what are endogenous pacemakers
internal body clocks
what is the main endogenous pacemaker in humans
suprachiasmatic nucleus (SCN) - cluster of neurons in the hypothalamus above the optic nerve, one in each hemisphere
what does the SCN do
sends signals to the pineal gland to increase production of melatonin at night - melatonin makes us sleep by inhibiting neural mechanisms that promote wakefulness
what are exogenous zeitgebers
environmental/external cues which affect our biological body clock
what is the main zeitgeber that affects our sleep/wake cycle
light
how does light affect out body clock
information from the retina goes to the SCN informing it of the amount of light received - decreased light levels cause SCN to increase melatonin secretion, increased light levels stimulates SCN to decrease melatonin secretion
what is another exogenous zeitgeber other than light
social cues like mealtimes or social activities can compensate for a lack of light
what is research support for SCN
Folkhard et al (1985) - studied people living in a bunker for 12 weeks, Ps went to bed when clock indicated 11:45pm and wake up at 7:45am, researchers quickened the clock so only 22 hours passed, volunteers cycle continued to follow the 24 hr clock instead of the 22 hr clock, SCN had more effect than the clock
what are animal studies supporting SCN affecting the sleep/wake cycle
Stephan and Zucker damaged the SCN in rats, rats did not have the usual circadian pattern compared to rats with an intact SCN
Morgan (1995) removed SCN from hamsters and found their sleep/wake cycle disappeared, it was reestablished by transplanting SCN cells from foetal hamsters
what is research support for social cues
Luce and Segal - people living in the Arctic circle still sleep around 7hrs a night even though the sun never sets during summer, in certain circumstances external cues take over and dictate sleeping times: supports theory that social cues affect our biological rhythm
research support for light being an exogenous zeitgeber
Campbell and Murphy - effect of light on sleep/wake cycle when light is detected by skin receptors, not by the eyes: Ps’ woken at various times and a light shone on the back of knees, found that there was a change in their usual sleep/wake cycle by up to 3 hrs, suggests that light is a powerful zeitgeber that doesn't need to rely on the eyes to influence the brain and affect the sleep/wake cycle