Reducing sleep hours by just 90 minutes each night increases the risk of diabetes in women who are used to getting enough sleep, and this effect is even more pronounced in postmenopausal women.

This is according to a new study from Columbia University, published in the journal “Diabetes Care”.

The recommended amount of sleep for optimal health is between seven and nine hours a night, yet about a third of Americans sleep less than the minimum recommended amount. Previous studies have shown that reduced sleep can increase the risk of conditions such as cardiovascular disease and hypertension, but many have been conducted only in men or focused on short-term, severe sleep restriction.

The new study specifically looked at women because studies have shown that poor sleep may have a greater impact on cardiometabolic health in women than men.

The study

To examine the impact of mild, chronic sleep deprivation the researchers enrolled 38 healthy women aged 20-75, including 11 postmenopausal women, who typically slept at least seven hours each night. In the study, participants underwent two study phases in random order. In one phase they were asked to maintain adequate sleep, so they slept an average of seven and a half hours per night, in the other they were asked to delay bedtime by an hour and a half per night while maintaining their typical wake time, so they slept 6.2 hours per night . Each of the phases lasted six weeks. Adherence to sleep schedules was measured with wearable devices. Throughout the study, the researchers measured insulin, glucose and body fat.

Insulin helps regulate glucose in the body, and when the body’s cells develop resistance to insulin, they become less able to use it effectively, and a person’s risk for prediabetes and type 2 diabetes can dramatically increase.

According to the research, ea mild sleep deficit sustained for six weeks causes changes in the bodywhich increase the risk of diabetes in women.

“Throughout their lives, women face many changes in their sleep habits due to childbirth, parenting and menopause,” notes Marie-Pierre Sonze, lead author of the study and associate professor of nutritional medicine and director of the Center of Excellence for Sleep and Circadian Research at Columbia University.

Specifically, it was found that reducing sleep hours by 90 minutes for six weeks increased insulin resistance by almost 15% overall and by more than 20% in postmenopausal women. Fasting insulin levels increased in premenopausal women in response to sleep restriction, whereas both fasting insulin and fasting glucose levels tended to increase in postmenopausal women.

Although increased abdominal fat is a key factor in insulin resistance, the researchers found that the effects of sleep loss on insulin resistance were independent of any changes in body fat.