Association of CSF Orexin-A levels and nocturnal sleep stability in patients with hypersomnolence

Objective: To evaluate the associations between cerebrospinal fluid orexin-A (ORX) levels and markers of nocturnal sleep stability, assessed by polysomnography (PSG).

Methods: Nocturnal PSG data and ORX levels of 300 drug-free subjects (55% men, 29.9±15.5 years, ORX level 155.1±153.7 pg/ml) with hypersomnolence were collected. Several markers of nocturnal sleep stability were analyzed: wake and sleep bouts, sleep/wake transitions. Groups were categorized according to ORX levels, in two categories (deficient≤110; >110), in tertiles (≤26, ]26;254], >254), and compared using logistic regression models. Results were adjusted for age, sex and body mass index.

Results: We found higher number of wake bouts (43 vs 25, p<0.0001), sleep bouts (43 vs 25.5, p<0.0001) and index of sleep bouts/hour of sleep time, but lower index of wake bouts/hour of waketime (41.4 vs 50.6, p<0.0001) in subjects with ORX deficiency. The percentage of wake bouts <30sec was lower (51.3 vs 60.8%,...