A large-scale scientific study revealed that sleeping for approximately 7 hours and 18 minutes each night may represent the ideal amount of time to reduce the risk of insulin resistance, a condition that is a precursor to type 2 diabetes.
The results also showed that trying to compensate for lack of sleep during the weekend may be associated with an increased risk of glucose metabolism disorders in people who already sleep for longer than optimal periods during the weekdays.
The study, published in the journal BMJ Open Diabetes Research & Care, relied on an analysis of extensive observational data, and focused on the relationship between the duration of sleep during weekdays and the rate of glucose disposal from the body, which is an indicator used to estimate the degree of insulin resistance. A low indicator is a sign of an increased risk of insulin resistance, while high values indicate a lower risk.
The researchers explain that the estimated glucose disposal rate, known as eGDR, is a reliable indicator of insulin resistance. When its value drops below about 6 to 7 milligrams per kilogram per minute, the risk of insulin resistance increases, while values higher than 10 milligrams per kilogram per minute indicate a lower risk.
To analyze this relationship, the researchers studied data from 23,475 participants between the ages of 20 and 80, as this data was collected within the National Health and Nutrition Survey in the United States during the period extending from 2009 to 2023. Of these, data on sleep during the weekend was available for 10,817 participants.
The researchers classified weekend catch-up sleep into four categories: no catch-up, less than an extra hour, between one and two hours, or more than two hours. The estimated glucose disposal rate index was calculated using an equation based on measurements of waist circumference, fasting blood sugar level, and blood pressure.
Inverted curve
The data showed that the average glucose disposal index among participants was 8.23, while the average sleep duration during weekdays was about 7 hours and 30 minutes.
More than 48% of the study participants reported that they compensate for the lack of sleep during the weekend, as their average sleep duration on those days was about 8 hours.
After analyzing the data, the researchers discovered an inverted U-shaped pattern linking sleep duration and the glucose disposal index. The results showed that the best balance point is about 7 hours and 18 minutes of sleep per night.
The results showed that increasing the hours of sleep in people who sleep less than this limit is associated with a higher glucose disposal index, which means a lower risk of insulin resistance. As for people who sleep more than this limit, increasing hours of sleep was associated with a decrease in this index, which indicates a higher risk of insulin resistance, and this relationship was more evident in women and people between the ages of 40 and 59 years.
Additional statistical analysis also showed that people who sleep less than optimal during weekdays may benefit from compensatory sleep on the weekend. Getting an additional one to two hours of sleep on the weekend was associated with a higher glucose disposal index compared to people who did not replace sleep at all.
But results were different for people who slept more than optimally during weekdays. In this group, compensatory sleep of more than two hours on the weekend was associated with a lower glucose disposal index, even after taking into account possible influencing factors, such as lifestyle, ethnicity, marital status, and level of education.
Sleep patterns
Researchers point out that the relationship between sleep and metabolism appears complex and mutually influential. Researchers say it’s important to point out that there is a bidirectional relationship between sleep and metabolism. For example, poor blood sugar regulation has been associated with an increased likelihood of short or long periods of sleep, as well as sleep disturbances.
The researchers add that this “may create a potential vicious cycle, whereby metabolic disturbance disrupts normal sleep patterns, while abnormal sleep, including prolonged sleep, exacerbates metabolic-related health problems.”
Despite the importance of the results, the researchers stress that the study is observational in nature, which means that it is not possible to confirm a direct causal relationship between sleep duration and insulin resistance. They also acknowledged that the study relied on participants’ self-reported data on sleep duration, which could open up the possibility of some degree of inaccuracy. The researchers were also unable to rule out the possibility that glucose metabolism disorders themselves affect sleep patterns and not the other way around.
However, the researchers concluded that the results suggest that sleep patterns, especially compensatory sleep during the weekend, may play an important role in regulating diabetes-related metabolic processes. They believe that these data may help healthcare professionals take sleep patterns into account when managing the health of patients at risk of developing diabetes or who already suffer from it.
