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Author (up) Hanifin, J.P.; Lockley, S.W.; Cecil, K.; West, K.; Jablonski, M.; Warfield, B.; James, M.; Ayers, M.; Byrne, B.; Gerner, E.; Pineda, C.; Rollag, M.; Brainard, G.C. url  doi
openurl 
  Title Randomized trial of polychromatic blue-enriched light for circadian phase shifting, melatonin suppression, and alerting responses Type Journal Article
  Year 2018 Publication Physiology & Behavior Abbreviated Journal Physiol Behav  
  Volume in press Issue Pages  
  Keywords Human Health  
  Abstract Wavelength comparisons have indicated that circadian phase-shifting and enhancement of subjective and EEG-correlates of alertness have a higher sensitivity to short wavelength visible light. The aim of the current study was to test whether polychromatic light enriched in the blue portion of the spectrum (17,000K) has increased efficacy for melatonin suppression, circadian phase-shifting, and alertness as compared to an equal photon density exposure to a standard white polychromatic light (4000K). Twenty healthy participants were studied in a time-free environment for 7days. The protocol included two baseline days followed by a 26-h constant routine (CR1) to assess initial circadian phase. Following CR1, participants were exposed to a full-field fluorescent light (1x10(14) photons/cm(2)/s, 4000K or 17,000K, n=10/condition) for 6.5h during the biological night. Following an 8h recovery sleep, a second 30-h CR was performed. Melatonin suppression was assessed from the difference during the light exposure and the corresponding clock time 24h earlier during CR1. Phase-shifts were calculated from the clock time difference in dim light melatonin onset time (DLMO) between CR1 and CR2. Blue-enriched light caused significantly greater suppression of melatonin than standard light ((mean+/-SD) 70.9+/-19.6% and 42.8+/-29.1%, respectively, p<0.05). There was no significant difference in the magnitude of phase delay shifts. Blue-enriched light significantly improved subjective alertness (p<0.05) but no differences were found for objective alertness. These data contribute to the optimization of the short wavelength-enriched spectra and intensities needed for circadian, neuroendocrine and neurobehavioral regulation.  
  Address Department of Neurology, Thomas Jefferson University, Philadelphia, PA 19107, USA  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0031-9384 ISBN Medium  
  Area Expedition Conference  
  Notes PMID:30296404 Approved no  
  Call Number GFZ @ kyba @ Serial 2025  
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Author (up) 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.; Cain, S.W. url  doi
openurl 
  Title Increased sensitivity of the circadian system to light in delayed sleep-wake phase disorder Type Journal Article
  Year 2018 Publication The Journal of Physiology Abbreviated Journal J Physiol  
  Volume in press Issue Pages  
  Keywords Human Health  
  Abstract KEY POINTS: This is the first study to demonstrate an altered circadian phase shifting response in a circadian rhythm sleep disorder. Patients with Delayed Sleep-Wake Phase Disorder (DSWPD) demonstrate greater sensitivity of the circadian system to the phase delaying effects of light. Increased circadian sensitivity to light is associated with later circadian timing within both control and DSWPD groups. DSWPD patients had a greater sustained pupil response after light exposure. Treatments for DSWPD should consider sensitivity of the circadian system to light as a potential underlying vulnerability, making patients susceptible to relapse. ABSTRACT: Patients with Delayed Sleep-Wake Phase Disorder (DSWPD) exhibit delayed sleep-wake behavior 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 ( approximately 150 lux) between male patients with diagnosed DSWPD (n = 10; aged 22.4 +/- 3.3 years) and male healthy controls (n = 11; aged 22.4 +/- 2.4 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 phase of the melatonin rhythm was associated with greater magnitude of phase shifts, 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 behavioral therapy, including minimization of exposure to phase-delaying night-time light. This article is protected by copyright. All rights reserved.  
  Address Monash Institute of Cognitive and Clinical Neurosciences, School of Psychological Sciences, Monash University, Melbourne, Victoria, Australia  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0022-3751 ISBN Medium  
  Area Expedition Conference  
  Notes PMID:30281150 Approved no  
  Call Number GFZ @ kyba @ Serial 2026  
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