0170 Association Between Objective Metrics of Vigilant Alertness and Non-Restorative Sleep: Implication for the Role of Glymphatic Clearance

Abstract Introduction We recently demonstrated that psychomotor vigilance test (PVT) metrics are associated with psychological health [Wada H, J Sleep Res, 2025], although the neurological mechanisms underlying these associations remain unclear. A recent study reported that impaired glymphatic clearance (GC) after 24-hour sleep deprivation was more strongly associated with vigilant lapses, or the number of slower reactions, than with reaction time, as assessed by PVT [Einspänner E 2025]. Because impaired GC is linked to depression [Deng Z. 2025] and may contribute to non-restorative sleep (NRS)[Hauglund NL. 2025], we hypothesized that NRS would be associated with PVT metrics, particularly with attentional lapses. The aim of this study was therefore to examine associations between PVT metrics and NRS. Methods In this sub-analysis of the National Survey for the Work Style Reform of Long-Working Physicians in Japan, 1,082 participants with complete PVT and traffic-accident data were included. NRS was assessed with the question, “How often have you had restorative sleep per week over the past 30 days?” Responses were coded as: never (0), 1 day (1), 2 days (2), and ≥3 days per week (3), and treated as a continuous variable. Physicians also reported their average sleep duration over the test week. A brief computerized 3-min PVT was administered after their shift, and PVT metrics, including mean reaction time (RT), lapses, and the PVT-likelihood ratio metric (PVT-LRM), were derived. Covariates included age, sex, body constitution, sleep duration, and the PVT testing time. Univariable and multivariable linear regression models were used. Results NRS was significantly associated with mean RT, lapses, and PVT-LRM. The association between NRS and lapses remained significant and robust after adjustment for sleep duration and PVT testing time (estimate [95% CI]: 0.015 [0.003–0.027], p < 0.05). Because sleep duration and testing time are indicators of sleep insufficiency, these results suggest that NRS is associated with vigilance lapses independently of sleep insufficiency, whereas the association between NRS and RT appears to be mediated by sleep insufficiency. Conclusion NRS was significantly associated with vigilant lapses and reaction time on the PVT, but with distinct patterns. This dissociation may possibly reflect impaired glymphatic clearance differently. Support (if any)