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Increased sensitivity of the circadian system to light in delayed sleep�wake phase disorder

Watson, L.A., Phillips, A.J.K., Hosken, I.T., McGlashan, E.M., Anderson, C., Lack, L.C., Lockley, S.W., Rajaratnam, S.M.W. and Cain, S.W. (2018) Increased sensitivity of the circadian system to light in delayed sleep�wake phase disorder Journal of Physiology, 596 (24). pp. 6249-6261.

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Patients with delayed sleep�wake phase disorder (DSWPD) exhibit delayed sleep�wake behaviour relative to desired bedtime, often leading to chronic sleep restriction and daytime dysfunction. The majority of DSWPD patients also display delayed circadian timing in the melatonin rhythm. Hypersensitivity of the circadian system to phase-delaying light is a plausible physiological basis for DSWPD vulnerability. We compared the phase shifting response to a 6.5 h light exposure (~150 lux) between male patients with diagnosed DSWPD (n = 10; aged 20.8 ± 2.3 years) and male healthy controls (n = 11; aged 22.4 ± 3.3 years). Salivary dim light melatonin onset (DLMO) was measured under controlled conditions in dim light (<3 lux) before and after light exposure. Correcting for the circadian time of the light exposure, DSWPD patients exhibited 31.5% greater phase delay shifts than healthy controls. In both groups, a later initial melatonin phase was associated with a greater magnitude phase shift, indicating that increased circadian sensitivity to light may be a factor that contributes to delayed phase, even in non-clinical groups. DSWPD patients also had reduced pupil size following the light exposure, and showed a trend towards increased melatonin suppression during light exposure. These findings indicate that, for patients with DSWPD, assessment of light sensitivity may be an important factor that can inform behavioural therapy, including minimization of exposure to phase-delaying night-time light. © 2018 The Authors. The Journal of Physiology and 2018 The Physiological Society.

Item Type: Article
Authors :
Watson, L.A.
Phillips, A.J.K.
Hosken, I.T.
McGlashan, E.M.
Anderson, C.
Lack, L.C.
Rajaratnam, S.M.W.
Cain, S.W.
Date : 2018
DOI : 10.1113/JP275917
Uncontrolled Keywords : melatonin, melatonin, adult, Article, circadian rhythm sleep disorder, clinical article, controlled study, daytime somnolence, delayed sleep wake phase disorder, human, light exposure, male, priority journal, saliva, sleep deprivation, sleep disorder, sleep waking cycle, case control study, circadian rhythm, female, metabolism, young adult, Case-Control Studies, Circadian Rhythm, Female, Humans, Male, Melatonin, Sleep Disorders, Circadian Rhythm, Young Adult
Depositing User : Clive Harris
Date Deposited : 17 Jun 2020 00:48
Last Modified : 17 Jun 2020 00:48

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