Brandy Solheim1, Knut Langsrud2, Håvard Kallestad2, Morten Engstrøm3, Bjørn Bjorvatn4, Trond Sand3. 1. Department of Neuromedicine and Movement Science, Faculty of Medicine and Health Sciences, NTNU - Norwegian University of Science and Technology, N-7491, Trondheim, Norway. Electronic address: brandy.solheim@ntnu.no. 2. Department of Mental Health, Faculty of Medicine and Health Sciences, NTNU - Norwegian University of Science and Technology, Trondheim, Norway; Division of Mental Health Care, St. Olavs Hospital HF, Trondheim University Hospital, Norway. 3. Department of Neuromedicine and Movement Science, Faculty of Medicine and Health Sciences, NTNU - Norwegian University of Science and Technology, N-7491, Trondheim, Norway; Department of Neurology and Clinical Neurophysiology, St. Olavs Hospital HF, Trondheim University Hospital, Norway. 4. Department of Global Public Health and Primary Care, University of Bergen, Bergen, Norway; Norwegian Competence Center for Sleep Disorders, Haukeland University Hospital, Bergen, Norway.
Abstract
STUDY OBJECTIVES: Difficult 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 as well as investigate a possible relationship with sleep stages. A secondary objective was to compare habitual sleep measured by polysomnography and actigraphy between patients and controls. METHODS: Twenty 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. RESULTS: Mean 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), however no further differences between the groups were observed regarding sleep structure. CONCLUSIONS: A high 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.
STUDY OBJECTIVES: Difficult 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 as well as investigate a possible relationship with sleep stages. A secondary objective was to compare habitual sleep measured by polysomnography and actigraphy between patients and controls. METHODS: Twenty 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. RESULTS: Mean 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), however no further differences between the groups were observed regarding sleep structure. CONCLUSIONS: A high 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.