It’s generally well known that getting a good night’s sleep makes us feel sharper, happier, and more energized. What’s less widely appreciated is that how well - and how long - we sleep may also play an important role in preventing or managing a variety of chronic illnesses, like diabetes. For decades, scientists have been learning about the “sleep–metabolism connection,” and the evidence is now clear: sleep isn’t just rest, it’s one of the body’s most powerful regulators of blood sugar.
During the night, your body quietly carries out vital work: balancing hormones, repairing tissues, and resetting your metabolism. When sleep is cut short, these processes take a hit. In one influential experiment at the University of Chicago, young, healthy adults who were limited to fewer than five hours of sleep a night for just one week showed dramatic changes in blood sugar regulation that looked strikingly like early diabetes. Large population studies have confirmed this link. The long-running Nurses’ Health Study, which followed more than 70,000 women for a decade, found that those who routinely slept fewer than six hours each night were far more likely to develop type 2 diabetes, even when accounting for diet, exercise, and weight.
At the center of this connection is insulin, the hormone that moves sugar out of the bloodstream and into cells for energy. Sleep loss reduces insulin sensitivity, leaving blood sugar levels elevated and forcing the pancreas to work harder. At the same time, the body’s stress hormone, called cortisol, tends to rise, making blood sugar control more difficult. Appetite-regulating hormones also fall out of balance: ghrelin, which stimulates hunger, rises, while leptin, which signals satiety, drops. Together, these changes encourage overeating and cravings for calorie-dense foods, further amplifying weight gain and insulin resistance.
It might seem that if too little sleep is harmful, more sleep must be protective. Surprisingly, that’s not the case. Research has found that these findings follow a U-shaped pattern: both short sleepers (fewer than six hours) and long sleepers (more than nine hours) face a greater risk of developing type 2 diabetes. Researchers suspect that long sleep may sometimes signal underlying health problems, low activity levels, or disruptions in the body’s internal clock. The takeaway is that balance matters: aiming for seven to nine hours seems to be the sweet spot.
Beyond sleep duration, sleep quality is equally important. Obstructive sleep apnea is a condition in which breathing repeatedly stops and starts at night. This can fragment sleep and lower oxygen levels. Findings from the large Sleep Heart Health Study showed that people with severe sleep apnea were more than twice as likely to develop type 2 diabetes compared with those without the disorder. The relationship goes both ways: diabetes can worsen sleep apnea through weight gain and nerve changes that affect breathing, while untreated apnea makes blood sugar harder to control. Encouragingly, research suggests that treating apnea with CPAP, a device that keeps the airway open, not only improves rest but may also enhance insulin sensitivity and stabilize glucose levels.
Certain groups may be especially vulnerable to the effects of poor sleep. Teenagers, whose body clocks naturally shift later, often experience chronic sleep deprivation thanks to early school start times. Researchers believe this mismatch may contribute to rising rates of obesity and prediabetes in adolescents. Older adults, meanwhile, often experience lighter, more fragmented sleep that can worsen insulin resistance. And women after menopause may also face elevated risk, as hormonal changes affect both sleep quality and metabolism.
The encouraging news is that small, everyday changes can make a meaningful difference. Experts recommend aiming for seven to nine hours of quality sleep each night and sticking to a consistent schedule, even on weekends. Creating a bedtime routine, which can look like limiting screens, caffeine, and heavy meals late at night, helps signal to the body that it’s time to wind down. Regular physical activity during the day improves both sleep quality and insulin sensitivity. And if you snore heavily, wake up gasping, or feel unusually tired during the day, seeking evaluation for sleep apnea is an important step. Diet and exercise rightly dominate the conversation about diabetes prevention, but sleep is a third pillar of health that deserves equal attention. By prioritizing sleep, you’re not simply resting! You’re giving your body the opportunity to regulate blood sugar, reduce the risk of diabetes, and support long-term well-being.
References
Ayas, Najib T et al. “A prospective study of self-reported sleep duration and incident diabetes in women.” Diabetes care vol. 26,2 (2003): 380-4. doi:10.2337/diacare.26.2.380LEGAL DISCLAIMER: Material in this newsletter is provided for general health education and informational purposes and to provide references to other resources only; it may not apply to you as an individual. While Apria Healthcare believes that the information provided through this communication is accurate and reliable, Apria Healthcare cannot and does not make any such guarantee. It is not intended to be a replacement for professional medical advice, evaluation, diagnosis, services or treatment (collectively, “medical treatment”). Please see your healthcare provider for medical treatment related to you and your specific health condition(s). Never disregard medical advice or delay seeking medical care because of something you have read on or accessed through this website. Reading this newsletter should not be construed to mean that you have a healthcare provider/patient relationship.