Your Midnight Snacking Habit Won't Throw Your Sleep Schedule Off

We keep hearing that late snacks wreck your sleep, but the science doesn't back that up.


Here’s one reason not to feel guilty about that 11PM binge on leftover kung pao chicken: it probably won’t keep you up.

Aa paper published Thursday in the journal Current Biology played down concerns that irregular meals disrupt a bodies internal rhythm and risk wrecking sleep cycles. Researchers at the University of Surrey in the U.K. put ten healthy young men through a 13-day ringer in a lab. The scientists fed the men the same, boring-sounding breakfast half an hour after waking every day. Lunch and dinner followed. Then, at the end of several days of that meal cycle, the men went through a 37-hour battery of tests to measure their bodies’ rhythms.

The men then endured six more days of eating in the lab, with a twist: This time, breakfast was delayed by five whole hours. Lunch and dinner were set back too. When the six days were up, it was time for a 37-hour battery of tests again.

The researchers trumpet the result that they did find some change to the chemical rhythms of the body between the first cycle and the second — kinda, sorta, maybe.

After switching from the early meal cycle to one five hours delayed, the men’s blood sugar regulation was a tad off-kilter. But there was no effect to sleeplessness, melatonin (a sleep related hormone) in the blood, or any other measurable physiological daily cycles. One “clock gene” of several that the human body uses to track the rhythms of the day was also delayed — by one hour.

Sugar in the bloodstream was affected directly because of the biomechanics of how food gets processed in the digestive system. The researchers note that a full five-hour shift to match the delayed meals was bigger than they expected, but seeing some effect here isn’t exactly shocking.

The more interesting result is the one the researchers don’t highlight: Even a wild, five-hour disruption to your meal schedule won’t disrupt your body’s sleep clock in any measurable way at all.

You probably should still avoid chowing down at 11 PM every night. People tend to make poorer nutrition choices when it gets late, and there’s reason to think late-night snacking can lead to weight gain. But it won’t make you lose a significant amount of zzz’s.

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