Bio psych- bio rhythms Flashcards
What is a biological rhythm
A biological rhythm is any change in a physiological activity that repeats periodically in a set pattern.
What is a circadian rhythm
One cycle that lasts approx one day
What is an infradian rhythm
One cycle that takes longer than 24 hours
What is an ultradian rhythm
One cycle that takes less than 24 hours
What is an example of a circadian rhythm
sleep/wakingbody tempmetabolic activity hormones
What is an example of an infradian rhythm
MenstruationhibernationSAD
What is an example of an ultradian rhythm
Feedingstages of sleepalertness
An infradian rhythm lasts _____ than 24 hours
more
What happens in the first 10-14 days of the menstrual cycle
Oestrogen and progesterone at the lowest levelsWhen bleeding stops FSH levels rise causing growth of ovarian follicles
What is the first 10-14 days of the menstrual cycle called
The follicular phase
What happens at day 14 of the menstrual cycle
Ovulatory phase starts with FSH signaling ovaries to produce oestrogen, which causes LM to surge and that releases the largest egg in the fallopian tubes, ready for fertilisation
What stage starts at day 14 of the menstrual cycle
Ovulatory phase
Ultradian rhythms last _____ than 24 hours
less
The pattern of human sleep moves systematically through different stages that repeat approximately every ___ minutes
90
What time does body temperature peak and at what temperature
Mid afternoon at about 37.1
What time does body temperature fall and at what temperature
Early hours of the morning (about 4 AM) at about 36.1
What three factors is body temp influenced by
Muscular activitydigestionheat lossheat production
What is an edogeneous pacemaker
Internal body clocks that influence the patterns of our biological rhythms. These may be genetic mechanisms.
Two examples of an edogenous pacemaker
Pineal gland SCN (superchiasmatic nucleus)
What are the five steps of the sleep wake cycle
1) SCN recieves info that light levels have dropped via the optic nerve 2) Pineal gland secretes melatonin which causes sleepiness 3) Melatonin enhances the production of serotonin 4) Brain activity falls5) You fall asleep
How long did Siffre spend in an underground cave, away from natural light/dark cycles
6 months
What did being away from natural light/dark cycles allow SIffre to investigate
What happens when the bodily sleep-wake cycle is allowed to ‘free run’ away from exogenous zeitgebers.
What happened to Siffre sleep wake cycle at first
It was very erratic
What did Siffres sleep wake cycles settle down to
A fairly regular pattern of between 25 and 30 hours
How many days did Siffre think he was underground for
151nearly 150
Evaluation of bio rhythms -evidence, Siffre
Spent 6 months in underground cave away from natural sleep wake cycleFormed his own cycle of between 25-30 hours Thought he was down there for 151 days, but was actually down for 179Shows how exogenous zietgeburs effect sleep wake cycle
Evaluation of bio rhythms -Issue with Siffre
Brief summary of Siffre’s method and the issue with his only participant being himself: generalisability / representativeness / androcentric / ethnocentric / population validity / external validity.
Evaluation of bio rhythms-Evidence, Ralph et al
Ralph et al. (1990)Took the SCN from a ‘mutant hamster’ who had a circadian rhythm which had mutated to 20 hours.They transplanted the mutant SCN into the brains of normal adult hamsters.The normal hamsters took on the circadian rhythms of the mutant hamsters.Despite the shortcomings of less scientific case study research findings, EPs do play an important role in regulating the sleep-wake cycle.
Evaluation of bio rhythms -Issues with Ralph et al
Animal study Evolutionary discontinuity etc etc
What are exogenous zietgeburs
external stimuli which provide information about elapsed time and prompt changes in bodily activity and the patterns of our biological rhythms.
What did Vetter et al study
The effect of changing light temp from 4000 kelvin to 8000 kelvin on the sleep-wake and activity-rest behaviour
What was the sample of Vetter et al’s study
54 participants 27 experimental group 27 control group
What method did Vetter et al use
27 experimental group experienced light change was compared to control group who remained at 4000 K throughout the 5 week study period Sleep logs continuously assessed sleep wake behaviour and activity patterns
What did Vetter et al find
Artificial blue enriched light competes with natural light as a zeitgebur While pts working under natural light (4000K) appeared to synchronise to natural dawn, those who were working under blue enriched (8000K) appeared to synchronise to office hours
What did Vetter et al conclude
Light is the dominant zietgebur for the human clock and blue enriched light is a potent zietgebur to be used with caution
EValuation of bio rhythms -Vetters work into exogenous zietgeburs
27 experimental group experienced light change was compared to control group who remained at 4000 K throughout the 5 week study period Sleep logs continuously assessed sleep wake behaviour and activity patternsArtificial blue enriched light competes with natural light as a zeitgebur While pts working under natural light (4000K) appeared to synchronise to natural dawn, those who were working under blue enriched (8000K) appeared to synchronise to office hours
Evaluation of bio rhythms -Methodological issues with Vetter’s work
Can’t control all light sources - when they’re going to and from work they’ll be surrounded by natural light outside.Lack of internal validity
Evaluation of bio rhythms- Contrasting evidence for zietgeburs, Luce and Segal
Argue light is over ridden People in artic circle remain consistent with sleep wake (averaging 7 hours a night) despite having 6 months of darkness in winter and 6 months of light in summerSocial factors that reset endogenous rhythms rather than light levels
Evaluation of bio rhythms - Individual differences in repsonse to EZ’s and EP’s
Age has an impact on how much sleep people need which in turn may influence how they respond to EZ’s and how their EP’s function (older people need less sleep than younger people). Personality also seems to play a role in levels of alertness at certain times of day which again might influence how they respond to EZ’s and how their EP’s function.
