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Published on: August 8, 2019
Internal desynchronization of circadian rhythms and tolerance to shift work
Alain Reinberg1, Israel Ashkenazi
1Unite de Chronobiologie, Paris, cedex 19, France. areinberg@wanadoo.fr
Chronobiology International
|July 16, 2008
Summary
Shift work intolerance is linked to circadian rhythm desynchronization. Poorly tolerant shift workers show more internal desynchronization, while tolerant workers and former shift workers exhibit better synchronization.
Area of Science:
- Chronobiology
- Occupational Health
- Sleep Medicine
Background:
- Shift work can lead to intolerance, characterized by sleep disturbances, fatigue, and mood issues.
- Individual susceptibility to internal desynchronization of circadian rhythms is a proposed mechanism for shift work intolerance.
Purpose of the Study:
- To test the hypothesis that internal synchronization of circadian rhythms is associated with shift work intolerance and its symptoms.
- To analyze existing time series data from shift workers to evaluate the relationship between circadian rhythm synchronization and tolerance.
Main Methods:
- Reanalysis of longitudinal time series data from 48 male Caucasian French shift workers (SW).
- Collected data included sleep-wake logs, grip strength, and oral temperature, measured 4-5 times daily for at least 15 days.
- Statistical analysis involved power spectra to determine circadian period (tau), t-tests, chi square, and correlation coefficients.
Main Results:
- Non-tolerant shift workers exhibited a greater number of desynchronized circadian rhythms (tau differing from 24 hours) compared to tolerant shift workers (chi square=38.9, p<.0001).
- Former shift workers, after returning to day work, showed reduced or absent symptoms of intolerance and internal desynchronization.
- Tolerant shift workers were older and had longer shift work durations, with a stronger correlation between age and duration.
Conclusions:
- Non-tolerant shift workers are particularly sensitive to internal desynchronization of their circadian organization.
- Maintaining circadian rhythm synchronization appears crucial for shift work tolerance.
- Interventions aimed at improving circadian alignment may benefit shift workers experiencing intolerance.
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