Losing just 90 minutes of sleep each night over time could significantly raise the risk of insulin resistance and type 2 diabetes in women

In our fast-paced world, cutting back on sleep often feels like the only way to keep up. But for women, especially those who are postmenopausal, skimping on rest could quietly increase their risk of developing type 2 diabetes. A new study published in the National Institutes of Health (NIH) has uncovered how chronic sleep deficiency can drive insulin resistance in otherwise healthy women. This discovery highlights the importance of sleep as an effective tool for diabetes prevention.

The study, published in Diabetes Care, focused solely on women—a population that is often underrepresented in sleep studies—and found that individuals who consistently slept 90 minutes less than usual each night had a significant rise in insulin resistance. Postmenopausal women were found to be particularly vulnerable.

“Women report poorer sleep than men, so understanding how sleep disturbances impact their health across the lifespan is critical, especially for postmenopausal women,” explained Marishka Brown, Ph.D., director of the National Center on Sleep Disorder Research at the National Heart, Lung, and Blood Institute (NHLBI), which co-funded the study alongside the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK).

The harmful link between sleep deprivation and health problems like heart disease, high blood pressure, and metabolic disorders is well-established. However, most previous research primarily involved men or investigated extreme, short-term sleep loss. This latest study breaks new ground by showing that even a modest, long-term reduction in sleep can impair glucose regulation in women.

Researchers recruited 40 healthy women, aged 20 to 75, all of whom had good sleep patterns (7-9 hours/night) and normal fasting glucose levels. Despite their health, these women had risk factors for metabolic diseases, such as overweight, obesity, a family history of diabetes, or cardiovascular issues. The goal was to understand how sleep loss over several weeks might affect their insulin and glucose levels.

Each participant underwent two separate six-week phases, with a six-week break in between. In one phase, they maintained their regular sleep schedule, averaging 7.5 hours per night. In the other phase, they delayed their bedtime by 1.5 hours each night, reducing their sleep to about 6.2 hours.

During both phases, participants underwent oral glucose tolerance tests to measure their blood glucose and insulin levels. Additionally, MRI scans were conducted to monitor body composition. The results were alarming: limiting sleep to around 6 hours a night led to a 14.8% increase in insulin resistance across the entire group. Postmenopausal women experienced an even steeper rise of up to 20.1%.

Insulin resistance occurs when cells become less responsive to insulin, a hormone that is responsible for regulating blood sugar levels. When this resistance develops, the body requires more insulin to keep glucose levels in check. Over time, this imbalance can lead to prediabetes and eventually type 2 diabetes.

Senior author Marie-Pierre St-Onge, Ph.D., director of the Center of Excellence for Sleep and Circadian Research at Columbia University, highlighted the concern: “What we’re seeing is that more insulin is needed to normalize glucose levels under sleep restriction. Even then, the insulin may not have been doing enough to counteract rising blood glucose levels in postmenopausal women.”

This data implies that prolonged sleep deprivation might speed up the progression of diabetes, particularly in people who are already at risk. Interestingly, researchers discovered that the harmful metabolic effects remained despite changes in body weight. While sleep-deprived participants often consumed more food, the spike in insulin resistance remained even when weight fluctuations were accounted for. The silver lining? Once participants resumed their usual 7-9 hours of sleep, insulin and glucose levels returned to normal range.

“This study provides new insight into the health effects of even small sleep deficits in women across all stages of adulthood and racial and ethnic backgrounds,” said Corinne Silva, Ph.D., Program Director at NIDDK. “Researchers are now planning further studies to explore how sleep deprivation affects men and women differently and whether improving sleep could serve as a strategy to prevent type 2 diabetes.”

These findings emphasize that sleep is not merely a luxury but a crucial component of metabolic health. For women, particularly after menopause, ensuring adequate sleep could be as crucial as proper nutrition and exercise in preventing diabetes. So, the next time you consider staying up late to catch up on work or scroll through your phone, remember—even those 30 extra minutes of rest might be protecting your future health.