An analysis of shiftwork and self-reported depressive symptoms in a police cohort from Buffalo, New York

Working Around the Clock: The Association between Shift Work, Sleep Health, and Depressive Symptoms among Midlife Adults

Shift work is an integral part of living in a 24-hour society. However, shift work can disrupt circadian rhythms, negatively impacting health. Guided by the Stress Process Model (SPM), this study examines the association between shift work and depressive symptoms and investigates whether sleep health (duration, quality, and latency) mediates this relationship among midlife adults. Utilizing data from the National Longitudinal Survey of Youth 1979 cohort (N = 6,372), findings show that working evening, night, and irregular shifts is associated with increased depressive symptoms. The results also show that part of the association between shift work and depressive symptoms among night and irregular shift workers, is indirect, operating through short sleep during the week and on the weekend. Although shift work can negatively affect mental health, getting more restorative sleep may mitigate part of the harmful mental health consequences of non-standard work schedules.

Systematic review of drugs that modify the circadian system's phase-shifting responses to light exposure

We searched PubMed for primary research quantifying drug modification of light-induced circadian phase-shifting in rodents. This search, conducted for work published between 1960 and 2018, yielded a total of 146 papers reporting results from 901 studies. Relevant articles were those with any extractable data on phase resetting in wildtype (non-trait selected) rodents administered a drug, alongside a vehicle/control group, near or at the time of exposure. Most circadian pharmacology experiments were done using drugs thought to act directly on either the brain's central pacemaker, the suprachiasmatic nucleus (SCN), the SCN's primary relay, the retinohypothalamic tract, secondary pathways originating from the medial/dorsal raphe nuclei and intergeniculate leaflet, or the brain's sleep-arousal centers. While the neurotransmitter systems underlying these circuits were of particular interest, including those involving glutamate, gamma-aminobutyric acid, serotonin, and acetylcholine, other signaling modalities have also been assessed, including agonists and antagonists of receptors linked to dopamine, histamine, endocannabinoids, adenosine, opioids, and second-messenger pathways downstream of glutamate receptor activation. In an effort to identify drugs that unduly influence circadian responses to light, we quantified the net effects of each drug class by ratioing the size of the phase-shift observed after administration to that observed with vehicle in a given experiment. This allowed us to organize data across the literature, compare the relative efficacy of one mechanism versus another, and clarify which drugs might best suppress or potentiate phase resetting. Aggregation of the available data in this manner suggested that several candidates might be clinically relevant as auxiliary treatments to suppress ectopic light responses during shiftwork or amplify the circadian effects of timed bright light therapy. Future empirical research will be necessary to validate these possibilities.