Please use this identifier to cite or link to this item: http://hdl.handle.net/2440/120387
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Type: Journal article
Title: Sleep regularity is associated with sleep-wake and circadian timing, and mediates daytime function in Delayed Sleep-Wake Phase Disorder
Author: Murray, J.
Phillips, A.
Magee, M.
Sletten, T.
Gordon, C.
Lovato, N.
Bei, B.
Bartlett, D.
Kennaway, D.
Lack, L.
Grunstein, R.
Lockley, S.
Rajaratnam, S.
Armstrong, E.
Chohan, K.
Djavadkhani, Y.
Dodds, K.
Gunaratnam, S.
Hardy, M.
Joosten, S.
et al.
Citation: Sleep Medicine, 2019; 58:93-101
Publisher: Elsevier
Issue Date: 2019
ISSN: 1389-9457
1878-5506
Statement of
Responsibility: 
Jade M. Murray … David J. Kennaway … M. Salkeld … et al. (for the Delayed Sleep on Melatonin (DelSoM) Study Group)
Abstract: Background: In healthy populations, irregular sleep patterns are associated with delayed sleep and poor functional/mood outcomes. Currently, it is unknown whether irregular sleep contributes to poor functional/mood outcomes in individuals with Delayed Sleep-Wake Phase Disorder (DSWPD). Methods: In 170 patients with DSWPD, we collected sleep-wake patterns, dim light melatonin onset (DLMO), and functional/mood outcomes. The Sleep Regularity Index (SRI) and other sleep timing metrics were computed. Correlations of SRI were computed with phase angle (difference between DLMO and desired bedtime), sleep timing and quality variables, daytime function, sleep-related daytime impairment, mood, and insomnia symptom severity. Path analyses assessed whether SRI or total sleep time mediated the associations between sleep onset time and phase angle with daytime functioning, sleep-related impairment, and mood outcomes. Results: Higher SRI was associated with earlier sleep and longer total sleep time, but did not relate to sleep quality, daytime function, or mood outcomes. Path analysis showed that phase angle was directly associated with all outcome variables, whereas sleep onset time was not directly associated with any. SRI mediated the effects of sleep onset time and phase angle on daytime function. Total sleep time mediated the effects of sleep onset time and phase angle on sleep-related impairment. Conclusion: Individuals with DSWPD who have more delayed sleep and a greater phase angle also have more irregular sleep. This suggests that it is not delayed sleep timing per se that drives poor functional outcomes in DSWPD, but rather the timing of sleep relative to circadian phase and resultant irregular sleep patterns.
Keywords: Variability; structural equation modelling; DSWPD; circadian rhythm sleep disorder
Rights: © 2019 Elsevier B.V. All rights reserved.
RMID: 0030117441
DOI: 10.1016/j.sleep.2019.03.009
Appears in Collections:Medicine publications

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