0627 Initial Use of the Sleep Inertia Questionnaire in Hypersomnolence Disorders

Abstract

Introduction: Sleep inertia can be defined as difficulty becoming fully awake after sleep. It has long been described as part of both idiopathic hypersomnia and mood disorders. Recently Kanady and Harvey developed the “Sleep Inertia Questionnaire” (SIQ) and validated it in patients with mood disorders, but not in disorders of hypersomnolence. We assessed SIQ performance in healthy controls and patients with a hypersomnolence diagnosis. Methods: Ninety-eight patients (mean age 37.5 (±14.8), 69.4% women) with diagnosis of narcolepsy type 1 (NT1, n=7), narcolepsy type 2 (NT2, n=14), idiopathic hypersomnia (IH, n=42), obstructive sleep apnea (OSA, n=16), and excessive daytime sleepiness not meeting criteria for a sleep diagnosis (EDSNOS, n=19) were included. Ten healthy controls (mean age 23.2 (±9.2), 80% women) were also included. All participants completed the SIQ and questionnaires assessing sleepiness (Epworth), fatigue (Fatigue Severity Scale), depression (Beck Depression Inventory), and chronotype (Horne-Ostberg). We used T-tests to compare groups, and Pearson correlations to investigate associations between the SIQ and other scales. Results: Patients with a hypersomnolence diagnosis scored significantly higher in all four subdomains of the SIQ compared to controls (p≤0.001 for all). They also scored higher on the BDI (9.1 vs. 2.0, p=0.002). IH patients had significantly higher scores on the behavioral subdomain of the SIQ compared to those with OSA (4.4 vs. 3.6, p=0.001), and significantly higher total scores compared to those with NT1 (14.0 vs. 10.8, p=0.03), despite comparable reports of depression on the BDI (OSA p=0.27, NT1 p=0.40). There were no differences between IH and NT2, or EDSNOS in any component of the SIQ (all p's >0.23). SIQ total score in IH patients showed a significant positive correlation with BDI, FSS, and hours slept per week (all p<0.001), but no correlation with ESS or Horne-Ostberg. Conclusion: SIQ scores may be elevated in all disorders of hypersomnolence, but less prominently in NT1 and OSA. The SIQ appears to be effective in detecting sleep inertia separately from sleepiness or chronotype, but may be influenced by concomitant depression.