Night workers who eat at night may suffer more symptoms of depression and anxiety. A study reveals the importance of adjusting our behavior to circadian rhythms.

Research led by scientists at Bringham Women’s Hospital, attached to Harvard University (United States), shows that the time you eat can affect your mental health, influencing the symptoms of depression and anxiety. The study reinforces the importance of respecting fixed schedules in the intakes and in the hours of sleeping and waking, so that they adjust to the body’s natural circadian rhythm, which is determined by internal factors and external modulators, such as sunlight, darkness or working hours.

EATING AT NIGHT INCREASES DEPRESSION AND ANXIETY

The researchers tested on two groups of participants the effects of eating during the day and at night, as many night workers do, or only during the day. They concluded that among members of the first group, which included nighttime intakes, depression levels were 26% higher and anxiety levels 16%.

People who only ate during daylight hours did not experience any increase in mood distress symptoms, suggesting that meal timing may influence the chances of suffering from a mild mental disorder. The results are published in the Proceedings of the National Academy of Sciences.

“Our findings provide evidence on the timing of food intake as a novel strategy to potentially minimize mood vulnerability in people experiencing circadian mismatch, such as people who work shifts, experience jet lag, or suffer from circadian rhythm disturbances,” said co-author Frank A. J. L. Scheer, director of the medical chronobiology program in the department of circadian and sleep disorders at Brigham Women’s Hospital.

“Further studies in shift workers and clinical populations are required to firmly establish whether 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 is important for our mood,” he added in the press release distributed by the medical center.

A PROBLEM FOR SHIFT WORKERS

In Spain, 14% of workers are organized in shifts and are responsible for many hospital and other essential services, in addition to factory work. Shift employees often experience a mismatch between their central circadian clock in the brain and daily behaviors, such as sleep/wake and fasting/meal cycles. Importantly, they have a 25 to 40 percent higher risk of depression and anxiety.

“Shift workers, as well as people experiencing circadian disruption, including jet lag, may benefit from a mealtime intervention,” said co-author Sarah L. Chellappa, of the Department of Nuclear Medicine at the University of Cologne.

“Our findings open the door to a new circadian behavior strategy in relation to sleep that could also benefit people experiencing mental health disorders. Our study adds to a growing body of evidence finding that strategies that optimize sleep and adjust circadian rhythms can help promote mental health.”

HOW WAS THE STUDY DONE?

To conduct the study, Scheer, Chellappa and colleagues recruited 19 participants (12 men and 7 women) for a randomized controlled study. The participants underwent a forced desynchronization protocol in low light for four 28-hour “days”, so that by the fourth “day” their behavioral cycles were reversed 12 hours, simulating night work.

Participants were randomly assigned to one of two mealtime groups: the day and evening meal group, which ate according to a 28-hour cycle (resulting in eating both day and night, which is typical among night workers), and the daytime only meal group in a 24-hour cycle.

The researchers assessed depression and anxiety levels every hour, and found that meal timing significantly affected participants’ mood. On the fourth day, participants in the day and evening meal group had increased levels of depression and anxiety. In contrast, there was no change in the mood of the group in which they only ate during the day. Participants with a higher degree of circadian mismatch experienced the highest levels of depression and anxiety.