The Optimal Sleep Duration for Preventing Type 2 Diabetes

Regularly getting just over seven hours of sleep – or, to be precise, around 7 hours and 18 minutes – per night could be a key factor in preventing type 2 diabetes. A recent study analyzing the relationship between sleep duration and metabolic health has pinpointed this amount of sleep as optimal for reducing the risk of insulin resistance, a precursor to type 2 diabetes.

Sleep Duration and Insulin Resistance

People who consistently get less than 7.3 hours of sleep per night, on average, have a higher risk of insulin resistance. Surprisingly, those who sleep more than 7.3 hours too face an increased risk. While a little extra weekend sleep can help mitigate the effects of insufficient weekday sleep, oversleeping on weekends can slightly raise insulin resistance for those already getting the optimal amount of sleep during the week.

“The take-home message is not that you need exactly seven hours and 18 minutes of sleep, but that roughly seven to eight hours of good quality sleep most nights is recommended for metabolic health,” says Scott Isaacs, MD, an endocrinologist and adjunct professor at the Emory University School of Medicine in Atlanta. “If you are consistently sleeping less than this, weekend catch-up of an extra hour or two may help, but it will not fully undo the impact of chronic weekday sleep deprivation.”

The Study Findings

Researchers analyzed data from nearly 25,000 people aged 20 to 80 between 2009 and 2023. They used a formula incorporating waist circumference, fasting blood sugar levels, and blood pressure to calculate the estimated glucose disposal rate (eGDR). Lower eGDR rates are associated with a greater risk of insulin resistance. These figures were combined with self-reported weekday sleep times, and a subset of about 11,000 participants also provided self-reported weekend sleep hours.

The research team found that, on average, 7.3 hours of sleep was the “sweet spot” for reducing the risk of insulin resistance. Insulin sensitivity improved as people approached this duration, then worsened when they slept beyond it. Women and adults aged 40 to 59 were particularly prone to insulin resistance if they slept more than 7.3 hours on weekdays.

Getting an extra one to two hours of sleep on the weekends was linked to lower insulin resistance risk for those not getting 7.3 hours of sleep on weeknights. However, more than two hours of weekend catch-up sleep was associated with higher insulin resistance risk for people already getting 7.3 hours of sleep during the week.

The Bidirectional Relationship Between Sleep and Metabolism

“This study reinforces that both too little and too much sleep are linked to insulin resistance,” says Dr. Isaacs. “The results suggest that modest catch-up may benefit people who are chronically sleep-deprived, but oversleeping on weekends is less helpful for those already above the optimal range.”

Zhanhong Fan, the lead study author and a researcher at Nantong University in China, highlights how common catch-up sleep is used as a coping mechanism. “This is likely due to ‘social jetlag,’ where shifting your sleep schedule significantly disrupts your body’s internal clock, leading to metabolic disturbances and poorer blood sugar control,” Fan explains. “But there is no weekend compensation for sleep. The healthiest approach for your metabolism is to prioritize consistent, moderate sleep over drastically varying your sleep schedule between weekdays and weekends.”

The Link Between Sleep and Diabetes

Research has long established a close connection between sleep and insulin resistance, prediabetes, and diabetes. Sleep is essential for regulating hormones, including those connected to glucose metabolism, such as cortisol and insulin. Studies have implicated sleep loss as a risk factor for developing insulin resistance and type 2 diabetes.

Sleep regularity and consistency are also key for heart health and metabolism. “Insufficient sleep alters hormones that are important signals regulating metabolism and energy balance,” says Peter Liu, MD, PhD, an endocrinologist and investigator of endocrinology and metabolic diseases at the Lundquist Institute for Biomedical Innovation at Harbor-UCLA Medical Center in California. “Maintaining cardiometabolic health through sufficient sleep contributes to longevity.”

Data suggests that an irregular sleep schedule can lead to a decrease in glucose tolerance and insulin sensitivity, contributing to prediabetes in otherwise healthy individuals.

Tips for Improving Sleep

“We want to emphasize that sleep is not passive rest; it’s an active, essential process for metabolic health. Viewing it as a critical part of a healthy lifestyle, alongside good nutrition and physical activity, is a crucial mindset shift,” Fan says.

• Be consistent with sleep and wake times, even on weekends. “If you are sleep-deprived, a modest weekend catch-up of one to two hours is okay, but avoid sleeping in for hours, which can disrupt your rhythm,” Fan says.
• Talk to your healthcare team about your sleep style. “Be specific about your patterns, such as, ‘I typically sleep six hours on weeknights and nine hours on weekends and still feel tired.’ Also ask if your sleep habits could be affecting your weight or blood sugar, and mention any concerns like loud snoring or excessive daytime fatigue,” Fan says.
• Put your devices away before bed. “Turn off all computers and cellphones an hour before you plan on going to sleep, and disconnect from the electronic world,” suggests a sleep expert.

Prioritizing consistent, moderate sleep is a vital step towards maintaining metabolic health and reducing the risk of type 2 diabetes.