Study Identifies Optimal Sleep Duration to Reduce Type 2 Diabetes Risk
A new study suggests 7 hours and 18 minutes of sleep may be optimal for reducing insulin resistance risk. The research found an inverted U-shaped relationship between sleep duration and glucose metabolism, with weekend catch-up sleep showing mixed effects.
A study published in the open-access journal BMJ Open Diabetes Research & Care on March 3 suggests that 7 hours and 18 minutes may be the "sweet spot" for reducing the risk of insulin resistance. Insulin resistance is when cells in muscles, fat, and liver don't respond properly to insulin, leading to a buildup of glucose in the blood. This is a precursor to type 2 diabetes.
The study included 23,475 participants, ages 20 to 80. The researchers set out to investigate the association between weekday sleep duration and estimated glucose disposal rate (eGDR), as well as the moderating effects of weekend catch-up sleep. eGDR is a measure of insulin sensitivity. The higher the eGDR, the lower the risk.
The researchers categorized weekend sleep as none, up to 1 hour, 1 to 2 hours, or more than 2 hours. They calculated the eGDR using a formula that involved waist circumference, glycated hemoglobin (HbA1c), and hypertension status.
The average eGDR was 8.23. Individuals slept for an average of 7 hours and 30 minutes on weekdays. A little over 48% of participants reported catching up on sleep on the weekend. They slept for an average of 8 hours during this time.
Analysis of the data showed an inverted U-shaped relationship between sleep duration and eGDR. The "sweet spot" appeared to be at 7 hours 18 minutes. Below this threshold, greater nightly sleep was associated with higher eGDR. Above the threshold, more nightly sleep was associated with a lower eGDR. This was particularly true among females and those between the ages of 40 to 59.
Further analysis showed that for those sleeping less than the optimal threshold during the week, 1 to 2 hours of catch-up sleep at the weekend was associated with a higher eGDR compared with no catch-up sleep. For those who slept more than the optimal threshold during the week, 2 hours of catch-up sleep at the weekend was associated with a lower eGDR after accounting for potentially influential factors, such as lifestyle, ethnicity, marital status, and educational attainment.
The researchers noted that there appears to be a bidirectional relationship between sleep and metabolism. Poor glycemic status itself has been linked to a higher likelihood of both short and extended sleep durations, as well as 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.
This was an observational study, which means that no firm conclusions about cause and effect can be drawn. The researchers acknowledged that the study relied on self-reported data. They also noted that they couldn't rule out reverse causation, meaning that disrupted glucose metabolism may interfere with sleep rather than the other way around.
The research team stated that these correlational findings suggest that sleep patterns, particularly weekend recovery sleep, may be relevant for metabolic regulation in diabetes and could inform considerations for healthcare professionals in managing patient care.