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BOSTON, MA – Sticking to daytime meals could be a key strategy for mitigating the increased cardiovascular risks often associated with shift work, according to a new study led by researchers at Mass General Brigham. The findings, published in Nature Communications, suggest that when people eat might play a more significant role in heart health than sleep timing when circadian rhythms are disrupted.
Shift work, particularly working through the night, has long been linked to a higher incidence of serious health issues, including cardiovascular problems. “Our prior research has shown that circadian misalignment—the mistiming of our behavioral cycle relative to our internal body clock—increases cardiovascular risk factors,” explained senior author Dr. Frank A.J.L. Scheer, Professor of Medicine and Director of the Medical Chronobiology Program at Brigham and Women’s Hospital. “We wanted to understand what can be done to lower this risk, and our new research suggests food timing could be that target.”
Inspired by animal studies showing that aligning meal times with the body’s natural active phase could lessen the health impacts of disrupted sleep-wake cycles, Dr. Scheer and his team designed a human trial.
Twenty healthy young adults participated in a rigorous two-week inpatient study at the Brigham and Women’s Center for Clinical Investigation. Kept in a controlled environment without external time cues like windows or personal electronics, researchers could isolate the effects of their internal body clocks.
Participants first underwent a “constant routine protocol” – staying awake for 32 hours in dim light with controlled posture and hourly identical snacks – to establish baseline measurements and separate circadian effects from environmental ones. They then engaged in simulated night work. Crucially, participants were randomly assigned to one of two groups: one group ate meals during both the simulated daytime and nighttime hours (mimicking typical night worker patterns), while the other group consumed all their meals strictly during the simulated daytime hours. Both groups followed identical nap schedules, ensuring sleep differences didn’t confound the results.
Following the simulated night work, another constant routine protocol assessed the aftereffects. Researchers measured key cardiovascular risk markers, including indicators of autonomic nervous system function, levels of plasminogen activator inhibitor-1 (PAI-1, linked to blood clot risk), and blood pressure.
The results were striking. Participants who ate during both day and night showed an increase in these cardiovascular risk factors compared to their baseline levels after the simulated night work. However, in the group restricted to daytime eating, these risk factors remained stable, showing no significant increase despite undergoing the same simulated night shift schedule. Notably, the total amount and type of food consumed were identical between the groups; only the timing differed.
“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,” stated lead author Dr. Sarah Chellappa, an associate professor at the University of Southampton.
While acknowledging limitations such as a small sample size (typical for such intensive controlled trials) and the study’s two-week duration, which may not fully capture chronic effects, the researchers highlighted the strength of the tightly controlled experimental conditions.
Drs. Scheer and Chellappa described the results as “promising.” While further research, particularly long-term studies, is needed, this study suggests that consciously timing food intake to daylight hours could be a practical intervention for improving the health of individuals facing circadian disruption. This could potentially benefit not only night shift workers but also those experiencing jet lag, insomnia, or other sleep-wake cycle disorders.
(Study Reference: Chellappa SL et al. Daytime eating during simulated night work mitigates changes in cardiovascular risk factors: secondary analyses of a randomized controlled trial, Nature Communications (2025). DOI: 10.1038/s41467-025-57846-y)
Disclaimer: This news article is based on findings from a specific scientific study published in Nature Communications. The information presented is for general informational purposes only and does not constitute medical advice. The study has limitations, and further research is needed to confirm these findings and understand long-term effects. Individuals, especially those working shifts or experiencing sleep disruptions, should consult with qualified healthcare professionals for personalized advice regarding their health, diet, and work schedules. Do not make changes to your lifestyle or medical treatment based solely on this information.
