0653 WORSENING PSYCHOMOTOR VIGILANCE AFTER BRIEF NAPS IN HYPERSOMNOLENT PATIENTS: MSLT NAP CORRELATES

Physiologic sleep inertia is operationalized as cognitive impairments upon awakening. Markedly pronounced sleep inertia, or sleep drunkenness, is common in idiopathic hypersomnia and may exist on a continuum with physiologic sleep inertia or may represent a distinct entity. Previous work has demonstrated significant worsening of vigilance on Psychomotor Vigilance Task (PVT) lapses (reaction times >500ms) and reciprocal of reaction time (RRT) following brief naps among hypersomnolent patients, but the MSLT correlates of these changes in vigilance are unknown. Patients undergoing PSG/MSLT (N=118; Age=37.38 ± 14.39; 62.71% women), with diagnoses of Idiopathic hypersomnia (n=37), Obstructive Sleep Apnea (n=29), Narcolepsy Type 1 (n=8) and Type 2 (n=6), and subjective sleepiness with normal MSLT (n=30), were administered PVT before and after MSLT naps 2 and 4. PVT performance was analyzed with paired t-tests, mixed-effects, and general linear models. For nap 2, lapses and RRT demonstrated significant worsening post-nap relative to pre-nap, (10.31 ± 18.56 [pre] vs 13.42 ± 20.65 [post]; t= -2.98, p=0.0035 and 3.24 ± 0.87[pre] vs 3.05 ± 0.91[post]; t=5.06, p= <.0001), respectively. Similar results were seen for nap 4 for lapses (t=-3.35, p=0.0011) and RRT (t=3.24, p=0.0016). Sleep duration on nap 2 was significantly associated with increased lapses (B=.80, S.E.=0.22, p=0.001) and worsened RRT (B=.03, S.E.=0.01, p=0.001) post-nap, but not on nap 4. Sleep efficiency on nap 2 was significantly associated with increased lapses (B=-8.57, S.E.=3.96, p=0.032) and worsened RRT (B=.38, S.E.=.14, p=0.006), but not on nap 4. Nocturnal PSG variables (sleep time, sleep efficiency, %N3 sleep, %REM sleep) and PSG/MSLT-based diagnoses were unrelated to PVT change in performance. Despite the generally short amount of accrued sleep time, psychomotor vigilance worsens immediately upon awakening from a morning MSLT nap in hypersomnolent patients, and this worsening is strongly related to amount of sleep obtained/sleep efficiency. This finding has implications for napping recommendations among those with excessive daytime sleepiness.