Meal timing alterations may prevent mood vulnerability in night shift workers

A recent study found that alterations made in meal timings can prevent mood vulnerability in shift workers. The study was published in the journal The Proceedings of the National Academy of Sciences. 

There is a 25 to 40% increased risk of developing depression and anxiety in shift workers due to a misalignment between the central circadian clock and daily environmental/behavioral cycles. These misaligned cycles may negatively affect mood and emotional well-being as impaired glycemic control is a risk factor for mood disruption. As the evidence-based circadian interventions to prevent mood vulnerability in shift work settings are lacking, researchers conducted a study to assess mood vulnerability during simulated night work with either daytime and nighttime or daytime-only eating as compared with simulated day work as the baseline.  

A parallel-design randomized clinical trial using a strictly controlled 14-d circadian laboratory protocol on healthy participants was carried out. Participants were randomized into two groups and underwent a forced desynchrony (FD) protocol in dim light for 4 "days" of 28 h, such that each 28-h FD day resulted in an additional 4-h misalignment between the central circadian clock and external behavioral/environmental cycles. The daytime and nighttime meal control (DNMC) group participants had a typical 28-h FD protocol, with behavioral and environmental cycles scheduled on a 28-h cycle, including the fasting/eating cycle, resulting in meals occurring during both the daytime and nighttime. In the daytime-only meal intervention (DMI) group, participants underwent a modified 28-h FD protocol with behavioral/environmental cycles scheduled on a 28-h cycle except for the fasting/eating cycle, which was scheduled on a 24-h cycle, thus resulting in meals consumed only during the daytime. Using computerized visual analog scales, depression-like and anxiety-like mood states were assessed.  

Key findings: 

•  Depression-like mood levels were increased by 26.2% and anxiety-like mood levels by 16.1% compared to baseline in simulated night work with daytime and nighttime eating. 
  
• There was no increase in anxiety-/depression-like mood levels with simulated night work in the daytime-only eating group.
  
• A larger degree of internal circadian misalignment was robustly associated with more depression-like and anxiety-like mood levels during simulated night work.

Thus, by this study, the researchers offered a proof-of-concept demonstration of an evidence-based meal timing intervention that may prevent mood vulnerability in shift work settings. 

To read the full article, click here: https://doi.org/10.1073/pnas.2206348119 

Qian J, Vujovic N, Nguyen H, et al. Daytime eating prevents mood vulnerability in night work. Proc Natl Acad Sci U S A. 2022;119(38):e2206348119.