Sleep Deprivation Can Raise Insulin Resistance in Women, Especially Postmenopausal Women
Key Highlights :
A study conducted by the National Institutes of Health has revealed that chronic insufficient sleep can raise insulin resistance in women, particularly postmenopausal women. The study, published in the journal Diabetes Care, highlights the importance of getting enough sleep in order to lower one's chances of developing type 2 diabetes.
Type 2 diabetes occurs when the body fails to effectively use the hormone insulin to maintain normal blood sugar levels. Lack of sleep can raise insulin resistance and glucose levels in women, increasing their risk of developing type 2 diabetes. The study was co-funded by the National Heart, Lung, and Blood Institute (NHLBI) and the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), both part of the National Institutes of Health.
Previous studies have shown that sleep restriction can elevate the risk of cardiovascular disease, hypertension, and disordered glucose metabolism, which can lead to insulin resistance and type 2 diabetes. However, many of those studies were conducted on men or focused on short-term, severe sleep restriction. The current study was done only on women and sought to determine if a prolonged, mild restriction of sleep - a reduction of just 1.5 hours each night - increased women's blood glucose and insulin levels.
The study enrolled 40 women, aged 20-75, who had healthy sleep patterns (at least 7-9 hours per night), normal fasting glucose levels, but had elevated risks for cardiometabolic disease due to having overweight or obesity or a family history of type 2 diabetes, increased lipid in the blood, or cardiovascular disease. To establish a baseline for the study, women wore a sensor on their wrists to record their sleep and determine their typical sleep patterns for two weeks and kept nightly sleep logs.
The women then completed two six-week study phases in a random order - one where they continued to follow their healthy sleep patterns, and one where sleep was restricted. During the adequate sleep phase, participants maintained their typical bed and wake times and slept for an average of 7.5 hours per night. In the sleep restriction phase, participants delayed their bedtime by 1.5 hours per night, while maintaining their typical waketime. During this phase, they slept 6.2 hours per night, which reflects the average sleep duration of U.S. adults with insufficient sleep.
At the beginning and end of each study phase, participants completed an oral glucose tolerance test to measure glucose and insulin blood levels, along with an MRI scan to measure body composition. The researchers found that restricting sleep to 6.2 hours or less per night over six weeks increased insulin resistance by 14.8% among both pre- and postmenopausal women, with more severe effects for postmenopausal women - as high as 20.1%.
In premenopausal women, they found that fasting insulin levels rose in response to sleep restriction, while levels of both fasting insulin and fasting glucose tended to increase in postmenopausal women. The researchers also looked at whether changes in body weight explained the changes they saw in insulin and glucose levels, as people tend to eat more in sleep-restricted states. However, they found that effects on insulin resistance were largely independent of changes in body weight, and once the women started sleeping their typical 7-9 hours per night again, the insulin and glucose levels returned to normal.
The 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. Researchers are now planning additional studies to further understand how sleep deficiency affects metabolism in men and women, as well as explore sleep interventions as a tool in type 2 diabetes prevention efforts.
