Biopsychology: Biological rhythms Flashcards
define the term biological rhythms
- periodic activity governed by endogenous pacemakers (internal biological clocks) and exogenous zeitgebers (external changes in the env)
state and describe are the types of rhythms (3)
- circadian rhythm - rhythm with a 24hr cycle
- ultradian - rhytm shorter than a day
- infradian - rhythm longer than a day
name 1 process which we have a circadian rhythm for and describe how this rhythm is governed by internal and external mechanisms (4)
- the sleep wake cycle
- exogenous zeitgebers: the fact we feel drowsy at night and alert during the day shows the effect of light (an external factor) on our internal body clock
- endogenous pacemakers: SCN receives information about light even when our eyes are closed = internal body clock
- pinneal gland: produces and releases diff amounts of melatonin in response to light levels which make us more or less alert
name a case study which supports circadian rhythms (1)
Michel Siffre
describe the procedure, findings and conclusion of Michel Siffre’s case study (6)
procedure:
- 2 months living in total isolation in alps
- no acces to clock, calendar or sunlight
- slept and ate only when his body told him to
findings
- his biological rhythm settles to just outside 25 hours
- natural fell asleep and woke up on a regule schedule
conclusion
- we have a circadian rhythm for sleep/wake cycle
who conduscted research which compared the effects of exogenous zeitgebers and endogenous pacemakers on the circadian rhythm ? (1)
Folkard
describe the procedure, findings and conclusion of Folkard’s research (5)
skprocedure:
- studied 12 ppl that lived in dark cave for 3 weeks
- went to bed when clock said 11:45pm and woke up when clock said 7:45am
- researchers gradually sped up the clock to a 22 hour day
findings
- only 1 ppnt adjusted to new regime
conclusion:
-sleepwake cycle is an example of a circadian rhythm
what are the 3 evaluation pointa for circadian rhythms ? (3)
✅ research support - Siffre
❌ cave case studies - very small sample size - small group of ppnts or just 1 individual + not easily replicated hard to determine reliability
❌ individual diffs not taken into account in research into circadian rhythm - research found that ‘morning people’ prefer to get up and go to bed early but ‘evening people’ prefer to wake and go to bed later- innate individual differences in circadian rhythms
give an example of an infradian rhythm (1)
the menstrual cycle
describe the menstrual cycle (5)
- lasts for approx 28 days
- during each cycle oestrogen lvls rise causing ovaries to develop and release an egg = ovulation
- after ovulation progesterone thickens lining of uterus preparing body for pregnancy
- if egg isnt fertilised and pregnancy doesnt happen the egg is absorbed into the body and the womb lining comes away = menstruation
- cycle repeats
what are pheromones (2)
- external factors that regulate the menstrual cycle
- chemicals which act like hormones outside body of the secreting idividual affecting behavior of recieving individual
who conducted research into infradian rhythms ? (1)
McClintock
describe the procedure and findings of McClintock’s research
procedure:
- 29 ppnts
- 9 of women had sample of pheromones taken from their armpit at diff stages in their cycle = odor donors
- 20 had pheromones rubbed on their top lip = odor reciever
findings:
68% of odor recievers reported changes to their cycle that brought them closer to cycle of their odor donor
conclusion:
exogenous zeitgebers may synchronise menstrual cycles
what are the 2 evaluation points for infradian rhythms (2)
✅ research shows evolutionary basis for pheromones synchronised menstrual cycles beneficial as all children would be born at same time so could be reared collectively
❌ McClintock issues with validity - factors such as diet, lifestyle + stress werent controlled + small sample size, other research failed to replicate this study
give an example of a ultradian rhythm (1)
stages of sleep
describe the stages of sleep (4)
- 90 minute cycle “the sleep escalator”
- 5 mins of light sleep - transition from wakefulnesss to sleep
- 65 mins of normal or non- REM sleep
- 20 mins of REM sleep (where we dream)
describe the light sleep stage of sleep (stage 1 + 2) (4)
- last around 5 mins
- can be easily woken
- in stage 1 brain waves are in high frequency + short amplitude = alpha waves
- in stage 2 alpha waves continue but there are occasional random changes in pattern = sleep spindles
describe the non-REM sleep stage - stage 3 and 4 (4)
- lasts around 65 mins
- cant be easily woken
- known slow wake sleep
- brain waves have lower frequency and higher amplitude
descirbe the REM (rapid eye movement) sleep stage - stage 5 (5)
- lasts around 20 mins
- body is paralysed but brain is most alert
- this is when we dream
- brain produces theta waves
- eyes occasionaly move around
who conducted research supporting ultradian rhythms ? (1)
Demend and Kleitman
describe the procedure and findings of Dement + Kleitman’s research (3)
procedure:
- measures brain activity using EEG
findings:
- REM sleep highly correlated with dreaming
- when ppl were woken up during REM stage ppl could recall v clearly what they dreamed compared to other stages of sleep
what are the evaluation points for ultradian rhythms
✅ dement and klietmans research high validity + scietific replicated on multiple occasions + use EEG’s scientific credibility
✅ knowledge on ultradian rhythms has practical value
slow sleep stage reduces with age and growth hormones are produced during slow sleep stage - this can explain impairments in older ppl, so relaxation medication can be developed to improve slow sleep stage which will prevent these impairements
❌/✅ lab study - ppnts attached to machinery - doesnt resemble ordinary sleep however ✅ control extraneous variables which may affect sleep eg temp + noise
