Researchers have discovered that eating only during daylight hours may reduce the risk of cardiovascular disease for night shift workers. A clinical trial led by Professor Frank Scheer at Brigham and Women's Hospital, Harvard Medical School, and published in the journal Nature Communications on September 9, indicates that meal timing could be more crucial for heart health than previously thought.
In the study, twenty healthy adults were kept in a time-free environment for two weeks to simulate the conditions of night shift work. Participants were split into two groups: one consumed meals during the night to mimic typical night shift eating patterns, and the other ate only during the day. According to The Independent, this approach allowed researchers to isolate the effects of meal timing on cardiovascular risk factors.
"Night shift workers can avoid the cardiovascular disease risk associated with shift work if they eat only during the day," the research team stated in their paper published in Nature Communications. "This suggests that meal timing may be a greater risk factor than sleep time in cardiovascular health related to shift work."
The researchers measured cardiovascular risk indicators, including autonomic nervous system markers and levels of plasminogen activator inhibitor-1—a protein that increases the risk of thrombosis. Findings revealed that participants who ate at night exhibited increased cardiovascular risk factors compared to their baseline measurements. In contrast, those who restricted their eating to daytime hours maintained their cardiovascular risk factors at pre-study levels.
Professor Scheer noted, "Effective countermeasures to the effects of night work or circadian misalignment on the cardiovascular system have not yet been established." He added, "We wanted to understand what can be done to lower this risk, and our new research suggests food timing could be that target," according to SciTechDaily.
Dr. Sarah Chellappa, an associate professor at the University of Southampton and lead author of the study, emphasized the robustness of their findings. "Our study controlled for every factor that you could imagine that could affect the results, so we can say that it's the food timing effect that is driving these changes in the cardiovascular risk factors," she said, according to The Independent.
Participants underwent a rigorous protocol where they were kept awake for 32 hours in a dimly lit environment before the simulated night shifts. During this period, they maintained a fixed posture and consumed identical snacks every hour. To assess the effects of circadian misalignment, participants were kept away from windows, clocks, and electronic devices.
The study highlights that shift work, which disrupts normal circadian rhythms, is a known risk factor for cardiovascular diseases, particularly increasing the likelihood of coronary heart disease. By adjusting meal times, night shift workers may mitigate some of these health risks.
"Avoiding or limiting eating during nighttime hours may benefit night workers, those who experience insomnia or sleep-wake disorders, individuals with variable sleep/wake cycles, and people who travel frequently across time zones," the research team concluded in their paper.
While the study presents promising results, the researchers acknowledge the need for further investigation. Limitations include the small sample size and the short duration of the study. "More research with larger samples and using people who actually follow shift work schedules is needed to show the long-term health effects of daytime compared to nighttime eating," the team stated.
Scheer and Chellappa remain hopeful about the implications of their research. "While further research is necessary to show the long-term health effects of daytime versus nighttime eating, our results are promising and suggest that people could improve their health by adjusting food timing," they said.
The amount and content of food were identical for both groups in the study, underscoring that meal timing—not calorie intake or diet composition—was the variable influencing cardiovascular risk factors. Both groups also had identical sleep schedules, ensuring that differences in results were not due to variations in sleep.
The research adds to a growing body of evidence suggesting that aligning meal times with the body's natural circadian rhythms is essential for cardiovascular health. Previous animal studies hinted at these benefits, and this study provides controlled, human data to support the hypothesis.
As shift work remains prevalent in many industries, these findings could have implications for public health recommendations. Adjusting meal timing may be a simple yet effective strategy for reducing the heightened cardiovascular risks associated with night shift work.
"Switching the timing of meals may lower the health risks associated with night shift work," the researchers stated, noting the potential for practical applications of their findings. By prioritizing daytime eating, shift workers might protect their heart health despite the challenges posed by irregular work hours.
The article was written with the assistance of a news analysis system.