A delayed sleep midpoint (≥2:30 AM) is independently associated with osteoarthritis prevalence in a representative sample of US adults, with each 30-minute delay beyond 2:30 AM associated with an 8% increased odds of osteoarthritis.
The relationship between sleep midpoint and osteoarthritis follows a 'J-shaped' nonlinear pattern with an inflection point at 2:30 AM.
Each 30-minute delay in sleep midpoint at or beyond 2:30 AM was associated with an 8% increased prevalence of osteoarthritis.
The study included 7,640 participants from NHANES 2015–2020, of whom 977 had osteoarthritis.
Propensity score matching and subgroup analyses confirmed the robustness of the association between delayed sleep midpoint and osteoarthritis.
Sleep timing was identified as a potentially modifiable factor relevant to osteoarthritis prevention and management.
This research suggests that the timing of sleep — specifically the midpoint of a person's nightly sleep cycle — is linked to the likelihood of having osteoarthritis, the most common form of joint disease. Using data from nearly 7,640 American adults surveyed between 2015 and 2020, researchers found that people whose sleep falls later in the night (with a midpoint at or after 2:30 AM) have progressively higher odds of having osteoarthritis. For every 30-minute delay in sleep midpoint past 2:30 AM, the odds of having osteoarthritis increased by about 8%. Importantly, this association held even after accounting for factors like age, lifestyle habits, other health conditions, and how long people slept. The relationship is not simply linear — it follows a 'J-shape,' meaning that sleeping earlier or at moderate times shows no significant association with osteoarthritis, but once sleep timing pushes past the 2:30 AM midpoint threshold, the risk rises steadily. The sleep midpoint is calculated as the halfway point between when someone falls asleep and when they wake up, so a person sleeping from midnight to 8 AM would have a midpoint of 4 AM. The findings were consistent across different demographic groups and were confirmed using additional statistical methods to rule out confounding. This research suggests that when people sleep — not just how long they sleep — may matter for joint health. Since sleep timing is a behavior that can potentially be changed (for example, by shifting bedtime earlier), this finding points to a possible practical avenue for osteoarthritis prevention that future studies could explore more directly through interventional trials.
Yang H, Liu W, Xiao C, Han Y, Lin X, Wu Y. (2026). Nonlinear relationship between sleep midpoint and osteoarthritis: a cross-sectional study in US adults.. Clinical rheumatology. https://doi.org/10.1007/s10067-025-07918-7