Biopsychology- Biological rhythms Flashcards
What are biological rhythms
Cyclical changes in body activity
Circadian rhythms definition
Type of biological rhythm that occurs every 24 hours- set and reset by environmental light
Endogenous pacemakers definition
Internal body clocks that regulate many of our biological rhythms
Exogenous zeitgebers definition
External cues that may affect our biological rhythms
Ultradian rhythms definition
Type of biological rhythm with a duration of over 24 hours
Infradian rhythms definition
Type of biological rhythm that lasts less than 24 hours
Example of circadian rhythm
Sleep/ wake cycle
Release of hormones
Body temperature
How do circadian rhythms stay in tune with the external world
Our internal body clock (endogenous rhythms) and external cues (exogenous zeitgebers) work together
What is the name of the endogenous pacemaker that controls the circadian sleep/ wake cycle
Suprachiasmatic nuclei (SCN)
How does the sleep wake cycle work - describe it using SCN
- light detected in eye, sends message to SCN
-SCN coordinates activity of circadian system
-sends signal to pineal gland to increase melatonin at night
-melatonin induces sleep
-SCN makes link btwn light and melatonin
What is meant by free-running
Our body clocks are left to their own devices in the absence of cues
What are the main exogenous zeitgebers for humans?
Light, diet, temperature
Does sleep occur when temperature rises or falls?
Rises- falls when waking up
A03- research into circadian rhythms
Siffre
- 6 months in cave (food + drink but lack of light and sound)
-free-running body clock = 25 hours
-sleep schedule was fine with absence of EZ
- so sleep/wake cycle is mainly controlled by EPs but EZs are essential to make 24 hour
Counter argument to Siffre
Lack pop validity: 1 guy, unique, found internal body clock ran slower- not generalisable
-idiographic, subjective
-highlights individual differences can affect
A03- research into endogenous pacemakers
Ralph- support importance of SCN in circadian rhythms
- SCN of genetically abnormal hamsters with CR of 20 hrs removed and implanted into normal hamsters
-CR shortened to 20 hours
-basic period is determined by SCN cells
Counter argument to Ralph
Extrapolation issues - external validity (to humans)
-many differences btwn animals and humans
-humans have more social cues can adapt
-cannot be certain humans would respond in the same way
A03- research into exogenous zeitgebers
-office workers
-exposed to blue light or warmer, artificial office light
-activity levels were monitored
-blue lights synchronised to office hours
-warmer light synchronise to natural dawn
-light is powerful
A03- practical applications
Knowledge of circadian rhythms- better understanding of consequences of their disruption
-accidents at work most likely to occur at night bc of light- sleep deprivation and concentration
- so should use blue light
REDUCES NEGATIVE CONSEQUENCES ASSOCIATED WITH SHIFT WORK
