0721 Association Between Subjective-Objective Sleep Time Discrepancy and Mortality in Older Men With/Without Insomnia

Abstract Introduction Subjective sleep duration often differs from objective measurements. Our prior research indicates that overestimating sleep duration may be a risk factor for all-cause mortality in older men. Conversely, those with insomnia, which is an another mortality risk factor, typically underestimate their sleep duration. This study investigates how both underestimation and overestimation of sleep duration impact all-cause mortality in community-dwelling older men (aged ≥ 65) comparing with and without insomnia symptoms. Methods We conducted a secondary analysis using data from the Osteoporotic Fractures in Men Sleep Study, involving 2,200 participants who underwent in-home polysomnography and completed surveys assessing their subjective sleep duration, without using sleep-affecting medication (such as antidepressants, hypnotics or benzodiazepines). Insomnia was defined by a Pittsburgh Sleep Quality Index (PSQI) score over 5 (N = 816). We examined the relationship between subjective-objective sleep duration discrepancy index (SODI) and mortality using Cox regression. SODI, the ratio of subjective to objective sleep duration, was analyzed categorically, comparing its lowest and highest quartiles to the interquartile range within each group. The study was approved by the Ethics Committee of the National Center of Neurology and Psychiatry. Results During follow-up periods (mean: 10.6 years for insomniacs, 11.2 years for non-insomniacs), 504 (61.8%) insomniacs and 774 (55.9%) non-insomniacs died. In the insomnia group, both the lowest (adjusted Hazard Ratio [HR], 1.31; 95% Confidence Interval [CI], 1.02–1.68) and the highest (adjusted HR, 1.31; 95% CI, 1.03–1.66) SODI quartiles were associated with increased mortality compared to the interquartile range. Conversely, in the non-insomnia group, only the highest SODI quartile showed a significant increase in mortality (adjusted HR, 1.30; 95% CI, 1.07–1.59), with the lowest quartile showing no significant mortality association (adjusted HR, 0.94; 95% CI, 0.78–1.14). Conclusion Results demonstrate the significant role of subjective-objective sleep duration discrepancy in long-term health outcomes in both the insomnia and the non-insomnia group. Further physiological studies may elucidate the mechanisms of subjective-objective sleep duration discrepancy on mortality. Support (if any) This study received a grant-in-aid for scientific research from the Ministry of Health, Labor and Welfare, Government of Japan (grant numbers #19FA1009 and #21FA1002).