Objective: To assess the diagnostic value of extended sleep duration on a controlled 32-hour bed-rest protocol in idiopathic hypersomnia (IH).
Methods: 116 patients with high suspicion of IH (37 clear-cut-IH according to multiple sleep latency test criteria and 79 probable-IH), 32 with hypersomnolence associated with a comorbid disorder (non-IH) and 21 controls underwent a polysomnography, modified-sleep latency tests and a 32-h bed-rest protocol. Receiver operating characteristic curves were used to find optimal total sleep time (TST) cut-off values on various periods that discriminate patients to controls.
Results: TST was longer in patients with clear-cut-IH than other groups (probable-IH, non-IH and controls) and in patients with probable-IH than non-IH and controls. TST cut-off best discriminating clear-cut-IH and controls was 19h for the 32-h recording (sensitivity 91.9%, specificity 85.7%) and 12h (100%, 85.7%) for the first 24h. The 19-h cut-off displayed a specificity and sensitivity of 91.9% and 81.2% between IH and non-IH patients. Patients with IH above the 19h cut-off were overweight, had more sleep inertia and higher TST on all periods compared to patients below 19h, while no differences were found for the 12h cut-off. An inverse correlation was found between the mean sleep latency and TST during 32-h recording in IH patients.
Interpretation: In standardized and controlled stringent conditions, the optimal cut-off best discriminating patients to controls was 19h over 32-h that allows a clear-cut phenotypical characterization of major interest for research purposes. Sleepier patients on MSLT were also the more severe in terms of extended sleep. This article is protected by copyright. All rights reserved.