Neurocognition After Perturbed Sleep (NAPS): A Protocol for an Experimental Study Examining the Impact of Sleep on Neurocognition, Functioning, and Clinical Indicators in People with Schizophrenia

IntroductionPeople with schizophrenia (SZ) display neurocognitive deficits that have been identified as predictors of poor functioning and disability. Previous reports have noted that these deficits are strikingly similar to the cognitive sequalae of poor sleep. Consistent with this observation, extensive animal and basic human research have strongly support the deleterious effects of poor sleep on neurocognition. Notably, insomnia and disturbed sleep (DS) are highly ubiquitous among people with SZ. Yet, there is scarce information about the potential impact of poor sleep on neurocognition in this population, with available studies using correlational or cross-sectional designs. MethodWe will employ an experimental, within-person, cross-over design to characterize sleep architecture, duration, continuity and quality along with their neurocognitive, functional, electrophysiological, and clinical sequalae in individuals with SZ. Participants will complete two overnight lab-based polysomnography examinations (two weeks apart) employing two sleep schedules: 1) undisturbed sleep (8 hours); and 2) perturbed sleep (4 hours). As part of each overnight sleep schedule, participants will complete brief EEG-indexed sleep-sensitive memory tasks pre- and post-sleep, a post-sleep neurocognitive test battery, as well as a three-day post-sleep digital phenotyping of physical activity, daily functioning, mood, symptoms, medication side-effects, and suicidal ideation via smartphones and actigraphy. DiscussionDespite their chronic and ubiquitous nature, the impact of insomnia and DS on neurocognition in SZ remain poorly understood and modeled. This lack of information hinders our ability to develop accurate treatment models and effective interventions for neurocognitive deficits in SZ. Our aim is to address these gaps in knowledge.