Wake-REM sleep transitions for measuring REM sleep disturbance: Comparison between narcolepsy, idiopathic hypersomnia and healthy controls.

This study tested a well-known but as yet nonoperationalized means for measuring REM sleep disturbance in patients with narcolepsy at night. We retrospectively analyzed polysomnographies of patients with narcolepsy with cataplexy (n = 18), narcolepsy without cataplexy (n = 12), idiopathic hypersomnia (n = 22) and healthy controls (n = 33) with regard to the number of wake-REM sleep transitions as a measurement for REM sleep disturbance at night. We found a significantly higher number of transitions between wake and REM sleep (14.17 ± 2.00) in patients with narcolepsy with cataplexy than in healthy controls (3.70 ± 1.00; p < 0.001) and patients with idiopathic hypersomnia (5.36 ± 1.00; p = 0.001). These results confirm previous findings that REM sleep disturbance is a specific phenomenon for narcolepsy with cataplexy. Additionally we found that wake-REM sleep transitions provide a useful marker for operationalizing and measuring this sleep disturbance. A possible mediating factor for this observation is the hypocretin-1 system, which is deficient in narcolepsy with cataplexy but intact in idiopathic hypersomnia. The number of wake-REM sleep transitions may thus become a useful additional means for the differential diagnosis of narcolepsy. [ABSTRACT FROM AUTHOR]