Provides understanding of what happens when circadian rhythms are disrupted - desynchonisation
Night workers in shift work experience reduced concentration at around 6am (circadian troughs) - mistakes and accidents are more likely (Boivin et al)
Shift workers 3x more likely to develop heart disease (Knutsson)
Therefore, research into circadian rhythms has real-world economic value
Counterpoint to shift work
Research into shift work uses correlational methods - difficult to establish whether desynchronisation is the cause of the negative effects - may be other factors
Solomon - high divorce rates may be due to sleep strain and other influences like missing family events
Therefore, may not be biological factors causing negative effects in shift workers
Medical treatment
Circadian rhythms coordinate basic processes like digestion and heart rate
They rise and fall during the day, leading to chronotherapeutics - using biological rhythms to help administer medication
E.g. Aspirin is most effective taken last thing at night - prevents heart attacks (Bonten et al)
Therefore, circadian rhythms can help increase effectiveness of drug treatment
Individual differences
Difficult to generalise
Aschoff and Wever, and Siffre's studies based on small samples
Sleep/wake cycles vary from person to person (Czeisler et al)
Vary from 13 to 65 hours
Duffy et al. - some people have a natural preference for going to bed and waking earlier ('larks') and vice versa ('owls')
Siffre - his own sleep/wake cycle had slowed over time
Therefore, it is difficult to use data for anything except averages, which may be meaningless