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Neuronal mechanisms of shift workers’ sleepiness
© Postnova and Robinson; licensee BioMed Central Ltd. 2011
- Published: 18 July 2011
- Shift Work
- Circadian Pacemaker
- Circadian Phase
- Multiple Health Problem
- Sleep Drive
In an attempt to use all 24 hours of the day, shift work is becoming increasingly popular. Long term shift work leads to multiple health problems, including higher risk of cardiovascular diseases, mood disorders, and diabetes. Other consequences include loss of concentration and increase of sleepiness resulting in accidents . Given the prevalence of shift work and the severity of the associated hazards, understanding of the mechanisms underlying sleepiness and predictions of shift workers’ fatigue would prove highly valuable. A number of mathematical models addressing these questions exist in a current literature. However, most of them are phenomenological and are limited to studying short-term effects of shift work; i.e., sleepiness only during the first couple of days on the shift .
Using this model the physiological mechanisms responsible for shift-related changes in sleepiness are examined in the simplest case of permanent shift work. In good agreement with experimental data sleepiness was shown to increase during the first days on the evening, night and early morning shifts. This is explained by the inability to sleep enough during the active circadian phase and the thereby increased homeostatic pressure. After this initial increase, sleepiness decreases, and stabilizes due to circadian entrainment to the new external cues provided by the shifts. The entrainment time and the degree of sleepiness are higher for the shifts leading to a stronger change of the circadian phase comparing to the no-shift situation. The performance of shift workers was shown to be improved by increasing lighting intensity at work place and by decreasing light during breaks. Altogether, this model has shown to be a powerful tool for the research of mechanisms of sleepiness, and for design of optimal shift schedules.
This work was supported by ARC and NHMRC.
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