You probably know the feeling of staying up later than you planned, then reaching for a snack before bed.
For many of us, the hours after dinner are when the fridge calls loudest. What happens on the clock before sleep may matter more than we think.
A new randomized trial from New York University found that every hour earlier adults with prediabetes went to bed, they lost about 1.3 pounds (0.6 kg) more over eight weeks.
The effect held even when their total sleep time did not change.
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The eight-week trial, published in Nursing Research in November 2026, followed 196 adults aged 21 to 64 who had prediabetes and slept less than 6.5 hours a night.
Half got a standard lifestyle program covering healthy eating, activity and stress.
The other half got the same program plus sleep coaching aimed at shifting bedtime earlier.
Sleep timing, not sleep duration, drove the weight difference.
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Each hour of earlier sleep onset tracked with roughly 1.3 pounds more weight lost.
Fasting blood sugar levels did not budge in either group.
Why timing may matter more than hours
The researchers point to what happens in the hours before bed.
Late at night, the body becomes less sensitive to insulin, the hormone that moves sugar out of the blood.
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Eating during that window can nudge the body toward storing more and burning less.
Falling asleep earlier may also cut exposure to evening screens and to the appetite signals that keep people grazing after dinner.
Both can push eating into the metabolically worst window of the day.
What the trial did not change
Despite the weight difference, fasting blood sugar stayed flat in both groups over the eight weeks.
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The researchers had hoped longer sleep would improve glucose control. It did not.
That gap matters because prediabetes is the stage before type 2 diabetes.
More than 2 in 5 US adults now have it, according to the CDC, and about 8 in 10 of them do not know.
What you can try tonight
The shift tested in the trial was gradual, not abrupt.
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Participants pushed bedtime a little earlier each week, paired with basic sleep hygiene.
A longer gap between dinner and lights out, dimmer evening light, and a consistent bedtime are the same tools the sleep coaches used in the trial.
None of this requires counting calories or buying anything.
Earlier research has pointed the other way too.
In a separate trial, cutting just over an hour of sleep each night led to measurable weight gain within six weeks.
Anyone with prediabetes who is working on weight should still talk with their doctor before changing routines or medication.
The new trial adds a small, free lever to the usual advice. Try moving bedtime 15 to 30 minutes earlier this week, then another 15 minutes next week.
This article is made and published by Ida-Marie Palm Varbæk, who may have used AI in the preparation.