Association between nonrestorative sleep and increased healthcare costs: a 6-year cohort study.

Nonrestorative sleep (NRS) refers to the subjective experience of not feeling refreshed after sleeping. Although associations between NRS and mental and physical health have been reported, their relationship with long-term healthcare costs has not been examined. This study investigated whether NRS is associated with increased long-term healthcare costs using a large-scale cohort dataset from Japan. We analyzed the annual health screening and medical claims data of 117,049 individuals enrolled in a health insurance association for civil engineering and construction workers. NRS was assessed in the 2018 health screening using a single item: "Do you feel refreshed after a typical night's sleep?" Annual healthcare costs were calculated using medical claims data from fiscal years (FY) 2018 to 2023. Mixed-effects models for repeated measures, including interaction terms, were used to examine the association between NRS and healthcare costs over time. Sex-stratified analyses were also performed. At baseline, 45.7% of participants reported NRS. From FY 2020 onward, healthcare costs were significantly higher in the NRS group than in the restorative sleep (RS) group. In FY 2023, the cost difference was JPY 18,468 (95% CI: 7,306 to 29,630). Interaction analysis revealed that the cost gap between the NRS and RS groups widened significantly over time. Similar trends were observed in the sex-stratified analysis. NRS is significantly associated with increased long-term healthcare costs, suggesting an important medical and economic impact. Screening for NRS during routine health checkups and providing early interventions may be beneficial in reducing healthcare costs.