How Sleep Affects Blood Sugar
Sleep gets less attention than food and exercise in diabetes care, but the amount and quality of sleep you get has a measurable effect on blood sugar. This article covers what the research shows, the sleep problems that are common in type 2 diabetes and the habits that help.
How much sleep adults need
The American Academy of Sleep Medicine and the CDC recommend at least seven hours of sleep a night for adults. CDC surveys find that about a third of American adults regularly get less than that.
What short sleep does to blood sugar
In laboratory studies, healthy adults who were limited to four or five hours of sleep for several nights became less sensitive to insulin, so their bodies needed more insulin to handle the same amount of glucose. Short sleep also raises the stress hormone cortisol and changes the hormones that control hunger, which makes people more likely to want high-carbohydrate foods the next day.
Large population studies point the same way. People who regularly sleep less than six hours a night have a higher risk of developing type 2 diabetes, and people with diabetes who sleep poorly tend to have higher A1C levels.
Sleep apnea
Obstructive sleep apnea causes breathing to stop and start many times during the night, which breaks up sleep and lowers oxygen levels. It is very common in people with type 2 diabetes, especially those who carry extra weight, and most cases are never diagnosed. Signs include loud snoring, gasping or choking during sleep, morning headaches and feeling sleepy during the day despite a full night in bed.
If any of these sound familiar, ask your doctor about a sleep study, many of which can now be done at home. Treatment, most often a CPAP machine, improves sleep and daytime energy and may help with blood pressure.
Blood sugar problems that disturb sleep
The relationship runs in both directions. High blood sugar makes the kidneys pass extra urine, which can mean several trips to the bathroom each night. Low blood sugar during the night can cause sweating, a racing heart or vivid dreams that wake you up. Nerve pain or restless legs, both more common in diabetes, can also keep people awake. If your sleep is broken for any of these reasons, mention it at your next visit.
Habits that help
- Keep a regular schedule, going to bed and getting up at about the same time every day, including weekends.
- Stop caffeine by early afternoon, since it can stay in the body for six hours or more.
- Be careful with alcohol in the evening. It disrupts sleep later in the night, and for people taking insulin or a sulfonylurea it can cause low blood sugar overnight.
- Finish dinner two to three hours before bed and keep late snacks small.
- Keep the bedroom dark, quiet and cool, and put screens away before bed.
- Get daylight and activity during the day, which helps set the body clock and supports deeper sleep.