Insufficient sleep syndrome: A single center (Bern) experience over 20 years in diagnosis and management

Insufficient sleep syndrome (ISS) is characterized by excessive daytime sleepiness due to chronic sleep deprivation. We assessed the "real-word" experience of a tertiary sleep center with its diagnosis and management. We retrospectively studied patients with probable ISS referred to the University Sleep-Wake-Epilepsy Center, Bern, between 2000 and 2021. Diagnosis was based on the International Classification of Sleep Disorders, 3rd edition, and classified as probable (criteria 1-4 fulfilled) or definite (criteria 1-5 fulfilled). We analyzed the impact of comorbidities on demographic and baseline characteristics and the effect of sleep extension on Epworth sleepiness scale (ESS) score and actigraphy measures. Among >12,000 patients, 238 had probable ISS. Median age was 34 years (IQR ±22), 45% were female and 82% had comorbidities. Demographic, clinical, and sleep-wake test characteristics were broadly similar between patients with and without comorbidities. Of 95 patients with follow-up, 49 improved after sleep extension and were classified as definite ISS. Compared with patients remaining probable ISS, definite ISS patients had lower follow-up ESS scores (8.5 (7.0-11.2) vs. 10.0 (8.0-14.0), p = 0.03). In definite ISS, time in bed increased by 36 min (p ≤ 0.001). These patients had shorter baseline minimum time in bed, but otherwise similar actigraphy measures. In this sleep-disordered population, ISS was difficult to confirm and likely underreported. Comorbidities may be less decisive for diagnosis than previously assumed. Increasing TIB from the individual baseline and avoiding extremely short sleep periords may be clinically relevant. To improve ISS management, a critical reappraisal of current criteria and standardized approaches are needed.