Lowering it

Does poor sleep raise blood sugar?

By GyroscopeUpdated November 14, 20264 sources

Yes, starting the next day. A week of 5-hour nights made healthy young men 11% less sensitive to insulin, and in another study a single 4-hour night cut insulin’s effect by about a quarter. Less sensitive means the same meal leaves more sugar in your blood. Protect your sleep before you buy any supplement.

Why it gets left out

Blood sugar advice is mostly about food, and a bit about exercise. Sleep feels like a separate department, something about energy and mood. But the hormone that moves sugar out of your blood, insulin, works less well after a short night, and that shows up within a day.

A week of short nights

In 2010, researchers studied 20 healthy men aged 20 to 35, most of the time inside a research clinic, with their food and activity controlled. First they spent at least 8 nights with 10 hours a night in bed. Then they got 5 hours a night for 7 nights. At the end of each stretch, the researchers measured how well insulin worked, using the gold-standard clamp test and a second method. Their insulin output stayed about the same, so nothing made up for the drop.

One short night

Another 2010 study kept 9 healthy adults, 5 men and 4 women, to 4 hours of sleep for a single night and compared it with a normal night. After the short night, their liver kept making sugar when insulin told it to stop, their muscles took up less, and the amount of sugar the researchers had to infuse to keep their blood steady dropped about 25%. Their fasting blood sugar didn’t change, so a morning finger stick wouldn’t have caught it.

Your muscles take up about 80% of the sugar insulin moves. A short night is like starting the day with the doors to those muscles half stuck. The sugar from breakfast still gets in, but it takes longer.

A late dinner adds to it

In 20 healthy young adults, eating dinner at 10 pm instead of 6 pm led to higher blood sugar overnight, with the same food and the same bedtime. The effect was biggest in people who usually went to bed early.

How sure are we?

The lab studies are clear that short sleep makes insulin work less well, at least for days. They’re small, and they were done in young, healthy people, mostly men. What years of short sleep do to diabetes risk comes from long-term studies of people’s habits, which can’t fully separate sleep from everything else in their lives. We think the short-term results are enough to put sleep on the list.

Sleep moves HRV too, covered on hrv.guide’s does more sleep raise HRV? The night’s effect on your morning number is on why is my blood sugar high in the morning?