A shift in meal time could have a dramatic effect on mental health

From physicians to hoteliers, everyone knows that working night shifts is a grueling task, both mentally and physically. It increases the risk of weight gain as one burns less energy – not to mention how missing out on sunshine can drag one into depression in the long run.

Researchers from Brigham and Women's Hospital have now come up with an effective solution to help night-shift workers balance their mood and emotional well-being while working those long and dark hours: daytime eating.

The study has been published in the Proceedings of the National Academy of Sciences.

"Our findings provide evidence for the timing of food intake as a novel strategy to potentially minimize mood vulnerability in individuals experiencing circadian misalignment, such as people engaged in shift work, experiencing jet lag, or suffering from circadian rhythm disorders," said co-corresponding author Frank A. J. L. Scheer, Ph.D., Director of the Medical Chronobiology Program in the Brigham's Division of Sleep and Circadian Disorders.

"Future studies in shift workers and clinical populations are required to firmly establish if changes in meal timing can prevent their increased mood vulnerability. Until then, our study brings a new 'player' to the table: the timing of food intake matters for our mood."

Food really is your medicine

19 participants, 12 men and seven women, participated in the study to work in a controlled trial. Over the course of two weeks, the first group ate during the daytime and nighttime hours, while the second group only ate during the daytime hours.

Researchers revealed that meal timing really had an impact on the participants' mood levels. On day 4, the Daytime and Nighttime Meal Control Group had increased depression-like mood levels and anxiety-like mood levels compared to day 1. However, no mood shifts and depression signs have been observed in the Daytime Meal Intervention Group during the simulated night shift. Researchers also noted that individuals with a higher degree of circadian misalignment were more prone to depression- and anxiety-like mood swings.

Overall, the team has found that depression-like mood levels increased by 26 percent and anxiety-like mood levels by 16 percent.

"Shift workers — as well as individuals experiencing circadian disruption, including jet lag — may benefit from our meal timing intervention," said co-corresponding author Sarah L. Chellappa, MD, PhD

"Our findings open the door for a novel sleep/circadian behavioral strategy that might also benefit individuals experiencing mental health disorders. Our study adds to a growing body of evidence finding that strategies that optimize sleep and circadian rhythms may help promote mental health."

"Meal timing is emerging as an important aspect of nutrition that may influence physical health," Chellappa added. "But the causal role of the timing of food intake on mental health remains to be tested. Future studies are required to establish if changes in meal timing can help individuals experiencing depressive and anxiety/anxiety-related disorders."

Study abstract:

Shift workers have a 25 to 40% higher risk of depression and anxiety partly due to a misalignment between the central circadian clock and daily environmental/behavioral cycles that may negatively affect mood and emotional well-being. Hence, evidence-based circadian interventions are required to prevent mood vulnerability in shift work settings. We used a stringently controlled 14-d circadian paradigm to assess mood vulnerability during simulated night work with either daytime and nighttime or daytime-only eating as compared with simulated day work (baseline). Simulated night work with daytime and nighttime eating increased depression-like mood levels by 26.2% (p-value adjusted using False Discovery Rates, pFDR = 0.001; effect-size r = 0.78) and anxiety-like mood levels by 16.1% (pFDR = 0.001; effect-size r = 0.47) compared to baseline, whereas this did not occur with simulated night work in the daytime-only eating group. Importantly, a larger degree of internal circadian misalignment was robustly associated with more depression-like (r = 0.77; P = 0.001) and anxiety-like (r = 0.67; P = 0.002) mood levels during simulated night work. These findings offer a proof-of-concept demonstration of an evidence-based meal timing intervention that may prevent mood vulnerability in shift work settings. Future studies are required to establish if changes in meal timing can prevent mood vulnerability in night workers.