Sleep structure and awakening threshold in delayed sleep-wake phase disorder patients compared to healthy sleepers

Publication date: Available online 9 March 2018
Source:Sleep Medicine
Author(s): Brandy Solheim, Knut Langsrud, Håvard Kallestad, Morten Engstrøm, Bjørn Bjorvatn, Trond Sand
Study ObjectivesDifficult early morning awakening is a primary symptom of delayed sleep-wake phase disorder (DSWPD), however, it remains poorly investigated. Our main objective was to quantify the awakening threshold in DSWPD-patients and healthy controls and investigate a possible relationship with sleep stage. A secondary objective was to compare habitual sleep measured by polysomnography and actigraphy between patients and controls.MethodsTwenty DSWPD patients and 16 controls had two polysomnographic recordings at a sleep laboratory. Participants followed their habitual sleep-wake schedule on the first night and a forced sleep-wake schedule (00:00 – 07:00 h) on the second night. We used a custom-made alarm clock was for the forced-night awakening, starting at 72 dB sound intensity which increased up to 104 dB.ResultsMean awakening threshold in dB was higher in patients compared to controls; 75.5 vs. 72.6, p = 0.01, and the difference could not be explained statistically by sleep-time. Patients who were in REM sleep upon attempted awakening had a higher awakening threshold compared to patients who were in NREM sleep; 80.0 vs 74.7, F = 6.4, p = 0.02. Patients had increased sleep onset latency both at home with actigraphy and by PSG during the first laboratory night (20.6 vs 12.1 min, p=0.004), but no further differences between the groups were observed regarding sleep structure.ConclusionsHigh early-morning forced awakening threshold in DSWPD was related to REM sleep. Sleep onset problems, even with habitual bedtimes, may also be an integral feature of DSWPD.



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