People who work at night and sleep during the day often experience circadian disruption and a mismatch between their natural body clock and their sleep and eating patterns. Staying awake when the wakefulness circadian rhythm is low and sleeping when it is high leads to sleep disturbances and poor health in the long term. Yet our society depends on night shift workers in areas such as manufacturing, energy, transportation, healthcare, law enforcement, the military, and other essential services.
In a new study, scientists at Brigham and Women’s Hospital, one of the founders of Mass General Brigham Healthcare, tested whether meal times affect shift workers’ susceptibility to depressed mood. They designed a study that simulated night work hours and then tested the effect of daytime and nighttime meals on participants’ levels of depression and anxiety.
To conduct the study, the researchers enrolled 19 participants (12 men and 7 women) in a randomized controlled trial. Participants underwent a forced dim-light desynchronization protocol for four 28-hour “days” so that by the fourth “day” their behavioral cycles were reversed by 12 hours, mimicking nighttime work conditions and causing circadian mismatch.
Participants were also randomly assigned to one of two meal timing groups: a day and night meal control group, who ate according to a 28-hour cycle (resulting in both night and day meals, which is typical for workers). night shifts), and a daytime-only meal intervention group that ate according to a 24-hour cycle (resulting in daytime-only meals). The team rated participants’ levels of depression and anxiety every hour.
The results of the study, published in the journal Proceedings of the National Academy of Sciences, showed that meal times significantly affected participants’ mood levels. During the simulated night shift (Day 4), participants in the day and night eating control group had increased levels of depressive-anxiety mood compared to baseline (Day 1). In contrast, no changes in mood were observed during the simulated night shift in the intervention group with daytime meals. Participants with a greater degree of circadian mismatch experienced more depressive- and anxiety-like moods.
“Our results suggest that meal timing is a novel strategy for potentially minimizing mood vulnerabilities in people experiencing circadian misalignment, such as shift workers, jet lag, or those suffering from circadian rhythm disturbances,” said study co-author Dr. Frank A. J. L. Scheer.