Why we should avoid late-night snacks

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Why we should avoid late-night snacks

Published: 10 Apr. 2025, 00:05

Audio report: written by reporters, read by AI

Jung Jae-hoon

The author is a pharmacist and food writer.

After a long day at work, it’s only natural to crave a late-night snack — especially for those who work the night shift. But it's best to resist the temptation. A new study from Brigham and Women’s Hospital at Harvard Medical School finds that limiting meals to daytime hours may help mitigate the health risks associated with working at night.

Published in the journal Nature Communications, the study involved 20 healthy adults. Though the sample size was small, the randomized controlled design enabled researchers to establish causality. Participants followed identical schedules for sleep, meals, light exposure, posture and activity, ensuring that the only variable was the timing of their meals. Over a 32-hour period, they stayed in dim lighting, remained in consistent positions, and ate identical snacks every hour before participating in a simulated night shift. One group was instructed to eat during both day and night; the other, only during the day.

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Night shifts have long been linked to elevated cardiovascular risk. To investigate this, researchers measured markers of autonomic nervous system activity, blood clotting risk (specifically, levels of plasminogen activator inhibitor-1), and blood pressure changes. They found that these risk factors increased only among those who ate during both the day and night. In contrast, participants who ate exclusively during the day showed no such changes — their levels remained consistent. The quantity and content of the meals were identical across groups; the only difference was when the food was consumed.

The findings echo a previous study by the same team in 2021. In that experiment, 19 young adults underwent simulated night shifts. Half were restricted to daytime meals, while the rest ate during both day and night, mimicking typical shift-work patterns. The results showed that those who ate only during the day maintained stable blood sugar levels, while those who ate at night as well saw a 6.4 percent increase from baseline.

Similarly, a 2020 U.S. study found that when young adults ate dinner at 10 p.m., they burned less fat and experienced a 20 percent increase in blood glucose levels compared to when they ate the same meal at 6 p.m. Elevated blood sugar poses serious health risks, potentially leading to diabetes, obesity, and cardiovascular disease.

Though the latest study was conducted over just two weeks, and further research is needed to examine long-term effects, the takeaway is compelling: simply shifting meal times to daylight hours — without reducing food intake—could help reduce the health risks of night work.

So, the next time you find yourself tempted by a late-night snack after a long shift, remember this: humans are diurnal creatures. If night shifts are unavoidable, the least you can do is skip the midnight snack.

Translated from the JoongAng Ilbo using generative AI and edited by Korea JoongAng Daily staff.