1. In this study, participants eating both during the day and night had increased depression and anxiety-like mood levels during simulated night work.

2. Furthermore, a higher degree of misalignment between circadian and behavior cycles was associated with increased depression and anxiety-like mood levels during simulated night work.

Evidence Rating Level: 2 (Good)

Shift, or overnight workers, account for a significant portion of the United States (US) workforce and serve in many essential services. Shift workers often experience misalignment between their circadian rhythm and environmental/behavioral cycles, which has been associated with higher risk of depression and anxiety. However, whether modulating certain behavioral cycles, such as eating, may modify mood vulnerabilities has not been well tested.

This was a parallel-design randomized control trial of 19 healthy, adult participants (12 men). Participants with history of depressive/anxiety-related disorders, smoking, and on any medications were excluded. Patients were randomized to either a daytime and nighttime meal control group or daytime only meal intervention group.  Simulation of night work was achieved by having participants in dim light for four 28-hour “days”, so that by the fourth day, their behavioral cycles were inverted by 12 hours. The primary outcome was depression and anxiety-like mood levels, which were assessed every hour using computerized visual analogue scales (VAS).

This study found that compared to baseline (day 1), patients with daytime and nighttime eating had increased depression- and anxiety-like mood levels (26.2% and 16.1% increase, respectively) during the simulated night shift (day 4), while the daytime eating only meal intervention group did not. However, this study was limited in its generalizability due to the small, restrictive, and homogenous patient population, as well as the short observational period. Nonetheless, the study design accounted for many potential behavioral confounders, and therefore, offers evidence toward the potential benefit of mealtime behavioral modifications that warrant further study.

 Click to read the study in PNAS

Image: PD

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