new research suggests.
Investigators at Brigham and Women’s Hospital, Boston, created a simulated nightwork schedule for 19 individuals in a laboratory setting. Participants then engaged in two different meal timing models – daytime-only meals (DMI), and meals taken during both daytime and nighttime (DNMC).
Depression- and anxiety-like mood levels increased by 26% and 16%, respectively, among the daytime and nighttime eaters, but there was no such increase in daytime-only eaters.
“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,” co–corresponding author Frank A.J.L. Scheer, PhD, director of the medical chronobiology program, Brigham and Women’s Hospital, Boston, said in a news release.
The study was published online in the Proceedings of the National Academy of Sciences.
Misaligned circadian clock
“Shift workers often experience a misalignment between their central circadian clock in the brain and daily behaviors, such as sleep/wake and fasting/eating cycles,” senior author Sarah Chellappa, MD, PhD, currently the Alexander Von Humboldt Experienced Fellow in the department of nuclear medicine, University of Cologne (Germany). Dr. Chellappa was a postdoctoral fellow at Brigham and Women’s Hospital when the study was conducted.
“They also have a 25%-40% higher risk of depression and anxiety,” she continued. “Since meal timing is important for physical health and diet is important for mood, we sought to find out whether meal timing can benefit mental health as well.”
Given that impaired glycemic control is a “risk factor for mood disruption,” the researchers tested the prediction that daytime eating “would prevent mood vulnerability, despite simulated night work.”
To investigate the question, they conducted a parallel-design, randomized clinical trial that included a 14-day circadian laboratory protocol with 19 healthy adults (12 men, 7 women; mean age, 26.5 ± 4.1 years) who underwent a forced desynchrony (FD) in dim light for 4 “days,” each of which consisted of 28 hours. Each 28-hour “day” resulted in an additional 4-hour misalignment between the central circadian clock and external behavioral/environmental cycles.
By the fourth day, the participants were misaligned by 12 hours, compared to baseline (that is, the first day). They were then randomly assigned to two groups.
The DNMC group – the control group – had a “typical 28-hour FD protocol,” with behavioral and environmental cycles (sleep/wake, rest/activity, supine/upright posture, dark during scheduled sleep/dim light during wakefulness) scheduled on a 28-hour cycle. Thus, they took their meals during both “daytime” and “nighttime,” which is the typical way that night workers eat.
The DMI group underwent a modified 28-hour FD protocol, with all cycles scheduled on a 28-hour basis, except for the fasting/eating cycle, which was scheduled on a 24-hour basis, resulting in meals consumed only during the “daytime.”
Depression- and anxiety-like mood (which “correspond to an amalgam of mood states typically observed in depression and anxiety) were assessed every hour during the 4 FD days, using computerized visual analogue scales.