Disruption of central and peripheral circadian clocks in police officers working at night

Working atypical schedules leads to temporal misalignments between a worker's rest-activity cycle and their endogenous circadian system. Several studies have reported disturbed centrally controlled rhythms, but little is known on shift workers' peripheral clocks. Here, we assessed central clock markers, urinary 6-sulfatoxymelatonin and salivary cortisol, and clock gene expression in 2 peripheral clocks, oral mucosa cells and peripheral blood mononuclear cells (PBMCs), in 11 police officers. Before working 7 consecutive nights, officers' centrally controlled rhythms were aligned to a day-oriented schedule. These rhythms were partially realigned to the shifted schedule and dampened after a week working nights. For peripheral clocks at baseline, Period (PER)1-3 and nuclear receptor subfamily 1, group D, member 1 (REV-ERB alpha) in oral mucosa cells had a significant mRNA peak in the afternoon, whereas in PBMCs, higher PER1-3 expression was observed at 10:00 compared with 19:30. After a week working nights, PER1-3 and REV-ERB alpha expression in oral mucosa cells lost rhythmicity, and in PBMCs, the morning/evening difference observed at baseline was lost. To our knowledge, this is the first study to demonstrate the disruption of several peripheral clocks in real shift workers. Molecular circadian disturbances are believed to have important clinical implications for the occurrence of shift work-associated medical disorders.-Koshy, A., Cuesta, M., Boudreau, P., Cermakian, N., Boivin, D. B. Disruption of central and peripheral circadian clocks in police officers working at night.