0599 Sleep Stage Transition Patterns Among Youth with CNS Disorders of Hypersomnolence

Abstract Introduction Narcolepsy type 1 (NT1) is associated with frequent sleep stage transitions during nocturnal sleep. In this study, we report the pattern of sleep stage transitions that occurs and its relationship to CSF-orexin levels among pediatric NT1 patients. Furthermore, we study the patterns of sleep stage transitions in patients with Narcolepsy Type 2 (NT2) and Idiopathic Hypersomnia (IH). Methods We conducted a retrospective, cross-sectional study of nocturnal polysomnograms (PSGs) of a cohort of patients ages 5-21 years with NT1 (n=160), NT2 (n=24), IH (n=28), and subjectively sleepy controls (n=115) collected at Boston Children’s Hospital, Boston, MA and University of Bologna, Bologna, Italy. We compared the patterns of transitions between different sleep/wake stages during the nocturnal PSG by diagnostic group as well as by CSF-orexin level (low ≤110 pg/ml; normal >110 pg/ml) using chi-square testing that was adjusted for multiple comparisons. Results NT1 demonstrated a pattern of transitions from wake and all sleep stages except N3 sleep vs. controls, NT2, and IH with frequent transitions between wake and N1 sleep and less frequent transitions from N1 sleep to N2 sleep. The NT2 group had a distinct pattern of transitions from N1 vs. controls with more frequent transitions to REM sleep and less frequent transitions to N2. The IH group showed a similar pattern of sleep/wake transitions vs. controls. The pattern of transitions for the low CSF orexin group was different for all sleep stages and wake vs. normal level with frequent transitions from N2 sleep and REM sleep to wake and N1 sleep. Conclusion Young NT1 patients have a unique pattern of transitions between sleep/wake states. These findings are further confirmed by CSF orexin level. NT2 patients have a pattern of sleep stage transitions more similar to controls with the exception of the transitions from N1 sleep suggesting dysregulation of this light sleep stage. In contrast, the IH group shows patterns of transitions between sleep stages and wake that are similar to controls. Overall, results support differing sleep phenotypes demarcating these patients with severe daytime sleepiness. Support (if any) National Institutes of Health grant 5K23NS104267-2 to K.M