It's not just beauty rest -- sleep duration and quality are some of the most powerful indicators of metabolic health.
And a new study may have pinpointed exactly how much sleep it takes to keep Type 2 diabetes at bay.
Research has long linked sleep duration and insulin resistance, a precursor to diabetes. Now, experts believe a specific number of hours and minutes per night can best keep insulin resistance under control.
The study's authors based their findings off data from over 10,000 participants, aged 20 to 80, collected between 2009 and 2023.
The researchers used advanced modeling to look at the participants' estimated glucose disposal rate (eDGR), a common measurement of insulin resistance, and the effects of sleep duration and variation. The higher the eDGR, the lower the risk of insulin resistance, and vice versa.
They found that the precise amount of sleep for optimal eGDR is 7.32 hours, or seven hours and 19 minutes. The full findings offered even more detailed insights about our sleep habits.
Results showed that sleeping less than the optimal seven hours and 19 minutes a night was associated with a higher eGDR, or less risk of diabetes.
Getting more sleep was associated with a lower eGDR, or a greater risk of diabetes, especially for women and those between the ages of 40 and 59.
The China-based researchers also focused on what they called "weekend catch-up sleep," or sleeping in on the weekend to make up for a weekday sleep deficit.
The benefits versus detriments of weekend catch-up sleep varied depending on what a person's weekday sleep schedule looked like.
In general, weekend catch-up sleep was only beneficial for those with a weekday sleep debt -- and even then only in moderation. (Like, one to two hours max.)
For people who already get the recommended hours of sleep during the week, sleeping in on the weekends actually lowered their eGDR, making them more susceptible to insulin resistance.
And the outcome was even worse for people who get more than the recommended amount of weekday sleep and then an additional two or more hours of weekend sleep.
The study's authors noted that these findings reveal how weekend catch-up sleep has a "dual, conditional effect -- beneficial only in moderation for those with sleep debt, but potentially harmful for others."
Crucially for patients with metabolic concerns, these results also "underscore the importance of personalized sleep recommendations."
Insulin resistance is another term for glucose build-up in the blood, which happens when cells in the muscles, fat and liver stop responding to insulin properly. It's often asymptomatic, but can lead to prediabetes and Type 2 diabetes if left unchecked.
Lifestyle changes, however, can help stop the progression of insulin resistance. And sleep habits are a good place to start.
One challenge that the researchers picked up on, however, is that poor glycemic health can disrupt sleep patterns and has been linked to sleep disorders.
"This creates a potential vicious cycle wherein metabolic dysregulation disrupts normal sleep patterns, and the resultant abnormal sleep (including extended duration) further aggravates metabolic health," the researchers noted this week in BMJ Open Diabetes Research & Care.
As Dr. Alex Dimitriu, a double-board-certified psychiatrist and sleep medicine practitioner who was not affiliated with the study, recently put it to Healthline: "Too much sleep is often linked to illness and depression, while too little sleep is linked to anxiety and insomnia."
He added, "Sleep loves regularity and rhythmicity -- and is one of the biggest metabolic levers we have."