Quantifying the effect of disrupted nocturnal sleep on motor activity profile of pediatric type 1 narcolepsy patients.

Study Objectives: Disrupted nighttime sleep (DNS) is a core symptom of type 1 narcolepsy (NT1), resulting from hypocretin neuronal loss. In this study we quantified the influence of DNS on NT1 children motor activity profile. Methods: Sixty-one drug-naïve NT1 children and adolescents (mean=12.47±3.56) underwent two weeks of actigraphy immediately prior to the diagnostic hospitalization. The second PSG night was analyzed and the following variables extracted: percentage of N1, N2, SWS and REM sleep, SE and PLMi. For a subsamples of patients (n=47) we also computed sleep transitions including: a) Wake index, b) NREM/2-3 to Wake/N1 index, c) REM/N2/N3 to Wake/N1 Index and d) Wake/N1 index. Activity profiles were processed by mean of functional linear modeling (FLM) to convert and analyze raw activity in functional form [1]. Results: The analysis show that the N1 sleep percentage has a significant influence on NT1 children’s motor profile with higher percentages of N1 sleep being associated with lower motor intensity between 12:00-14:00 and 18:00-20:00. Similarly, lower REM sleep percentage is associated with lower motor activity intensity between 11:00-13:00. On the contrary N2 and SWS percentage does not significantly influence the motor activity profile. SE displays a significant effect exclusively during the nocturnal period with lower SE being associated with higher nocturnal motor activity. Conclusion: These findings show that the N1 sleep percentage is linked to lower daytime activity levels. Combining information deriving from actigraphy and PSG in a single analytical framework allows characterizing the effects of DNS on children’s everyday life.