A recent observational study found that about 7 hours 18 minutes of sleep per night was associated with the lowest risk of insulin resistance, a key precursor to type 2 diabetes. The researchers used estimated glucose disposal rate (eGDR) as a proxy for insulin sensitivity (higher eGDR indicates better sensitivity) and collected self-reported weekday sleep and weekend catch-up sleep (none, up to 1 hour, 1–2 hours, or more than 2 hours). Average eGDR in the sample was 8.23, average weekday sleep was roughly 7 hours 30 minutes, and about 48% of participants reported weekend catch-up sleep, averaging around 8 hours on weekends.
Key findings
– Weekday sleep and eGDR followed an inverted U-shaped pattern, with the peak eGDR at approximately 7 hours 18 minutes per night. Below that point, additional sleep was associated with better eGDR; above it, more sleep correlated with lower eGDR.
– Weekend catch-up sleep modified this relationship: among people who slept less than the optimal weekday amount, 1–2 hours of weekend catch-up was linked to better eGDR compared with no catch-up.
– Conversely, for people already sleeping more than the optimal weekday amount, 2+ hours of weekend catch-up was associated with worse eGDR after adjusting for lifestyle factors, ethnicity, marital status, and education.
– Associations were stronger in women and in adults aged 40–59.
Why sleep affects metabolic health
Insulin resistance happens when muscle, fat, and liver cells respond poorly to insulin, allowing blood glucose to rise. Sleep and metabolism influence each other: disturbed glucose regulation can alter sleep, and both too little and too much sleep can harm metabolic health. Short sleep increases stress hormones (adrenaline, cortisol) and sympathetic activation, raising blood glucose; excessively long sleep can be linked to underlying illnesses, reduced activity, and poorer metabolic outcomes. Sleep disorders such as obstructive sleep apnea also increase metabolic risk.
Limitations
This study is observational and based on self-reported sleep, so it cannot prove cause and effect; reverse causation is possible (metabolic problems could disrupt sleep). The findings require confirmation in experimental and longitudinal studies.
Practical takeaways
– Aim for about 7 to 7.5 hours of sleep per night for metabolic benefits.
– Keep sleep schedules regular and avoid large weekday–weekend swings.
– If you’re chronically short on sleep during the week, a modest 1–2 hour weekend recovery may help; large amounts of extra sleep don’t appear beneficial.
– Screen for and treat sleep disorders (for example, obstructive sleep apnea).
– Continue prioritizing diet, exercise, and weight management, since these work together with sleep to reduce diabetes risk.
If you have concerns about insulin resistance or diabetes risk, discuss them with your healthcare provider.