BIO RHYTHMS Flashcards
CIRCADIAN RHYTHMS AO1
bio rhythm subject to a 24hr cycle (eg sleep wake cycle) + controlled by endo pacemakers, influenced by exo zeitgebers.
CIRCADIAN RHYTHMS AO3
SIFFRE: cave study, spent 6 months in a cave deprived of exposure to natural light + sound, but with adequate food + drink. His free running bio clock settles to ~25hrs + continues to sleep + wake on a regular schedule. TS existence of circadian rhythms HOWEVER cycle is governed by endogenous pacemakers + less so from exogenous zeitgebers ALSO bias (in his own study) + small sample ∴ can’t generalise findings
ASCHOFF + WEBER: studied pts living bunker w/ only electric light. allowed to turn on + off as they wished to fit their body clocks. Eventually their body clocks settled to 25-27 hrs. TS we use light source to adjust our pacemakers w/ enviro + the 24hr clock is not in line with our body natural rhythms. HOWEVER, pts given access to electrical lights under the assumption this would not affect their free running biological rhythms – CZEISLER: shows pts circadian rhythms can be adjusted, from 22 hrs to 28 hrs, using dim lighting ∴ TS artificial light in the caves may have been a confounding variable.
CIRCADIAN RHYTHMS PRAC APP
SHIFT WORK: CZEISLER applied research into working world by persuading a company who employed workers on shifts to make forward rotating shifts (switching from phase advance to phase delay) + incr time between rotations. After 9 months, factory output was at an all time high, + so were workers moral. ALSO, traditional shift work is seen to have neg implications on health. KNUTTSON found shift workers who worked more than 15 yrs where 3x more likely to develop heart disease than non shift workers. TMBB stress of adjusting to different sleep/wake patterns + poor quality of sleep during the day. TS idea research may have economic implication in terms of how to best manage worker productivity and moral.
INFRADIAN RHYTHMS AO1
Bio rhythm w/ less than 1 cycle in 24hr period (e.g, menstrual cycle, SAD + hibernation)
INFRADIAN RHYTHMS S.A.D
Triggered when daylight hours become shorter, persistent low mood bc too much melatonin secreted bc lack of light which is thought to have an effect on serotonin production → LIGTH = EXO ZEITGEBER
INFRADIAN RHYTHMS S.A.D PRAC APP
PHOTOTHERAPY: light box that stimulates v strong light in the morning + evening – thought to resent melatonin levels
EASTMAN: relieves symptoms in 60% of sufferers but placebo effect of 30% using a ‘sham neg ion generator’. TS it is somewhat effect as a treatment BUT recovery also has psychosomatic effects as people believe they are getting better.
TERMAN: 124 SAD pts exposed to bright light – morning , afternoon or placebo. Morning group showed 60% improvement in mood, afternoon = 30%, placebo = 5%. TS phototherapy is most effective in the morning however issues with the self report technique. Results also show SAD is in part affected by light (∴ governed by exo zeitgebers)
INFRADIAN RHYTHMS MENSTRUAL CYCLE
Regulated by hormones (endo pacemakers) that either promote ovulation / stimulate the uterus for fertilisation. ~28 days
INFRADIAN RHYTHMS MENSTRUAL CYCLE EVAL
Research suggests menstrual cycle is, to an extent, governed by exo zeitgebers (external factors). REINBERG: a woman spent 3 months in a cave w/ only a small lamp to provide light. found her menstrual cycle shortened from the usual 28 days to 25.7 days. TS the lack of light (exo zeitgeber) affected her menstrual cycle, + ∴ TS effect of external factors on infradian rhythms.
RUSSELL: found menstrual cycles became synchronised w/ other females through odour exposure. - sweat samples from 1 group rubbed onto the upper lip of another group. Despite the fact the 2 groups were separate, their menstrual cycles synchronised. TS synchronisation of menstrual cycles can be affected by pheromones, which have an effect on people nearby rather than on the person producing them. TS external factors must be taken into consideration when investigating infradian rhythms + perhaps IDA a more holistic approach should be taken, as opposed to a reductionist approach that considers only endogenous influences.
ULTRADIAN RHYTHMS AO1
bio rhythm with cycles occurring more than once in 24 hrs. (eg stages of sleep). Alternates between REM (rapid eye movement) + NREM (non-rapid movement) sleep + consists of 5 stages. Cycle starts at light sleep, progressing to deep sleep + then REM, where brain waves speed up + dreaming occurs. ~ 90 mins throughout the night.
ULTRADIAN RHYTHMS AO3
DEMENT + KLEITMAN: monitored sleep patterns of 9 pts in sleep lab. Brainwaves recorded w/ EEG (alcohol + caffeine consumption was controlled) REM highly correlated w/ experience of dreaming. Brain activity varied according w/ how vivid dreams were. Their dream also mirrored REM e.g, pts who dreamt about climbing exhibited vertical rapid eye movement. TS REM is associated with dreaming + there is a significant association between pattern of eye movement + dream. BUT, pts many pts didn’t report dreaming in REM _ som reported dreaming outside of REM ∴ suggests dreaming does not exclusively occur in REM
IND DIFF → TUCKER: found significant differences between pts in terms of the duration of each stage, particularly stages 3 + 4 (just before REM sleep). TS there may be innate individual differences in ultradian rhythms, which means that it is worth focusing on these differences during investigations into sleep cycles.
LACK OF ECO VALIDITY: when investigating sleep patterns pts subjected to a specific level of control + attached to monitors. This may be invasive for pts, leading them to sleep in a way that does not represent their ordinary sleep cycle.
Research shows amount of REM sleep is proportional to the immaturity of the offspring @ birth. SIEGEL: found platypus immature at birth has ~8 hrs REM sleep a day but dolphin who can swim at birth has no REM sleep. TS REM sleep stimulates brain regions used in learning. This may be important for normal brain development during infancy, which explains why infants spend much more time in REM sleep than adults.
