Reported light in the sleep environment: enhancement of the sleep diary
Received 8 November 2018
Accepted for publication 25 January 2019
Published 25 March 2019 Volume 2019:11 Pages 11—26
Checked for plagiarism Yes
Review by Single-blind
Peer reviewers approved by Dr Colin Mak
Peer reviewer comments 3
Editor who approved publication: Dr Sutapa Mukherjee
Elizabeth M Harrison,1 Abigail M Yablonsky,2 Alexandra L Powell,1 Sonia Ancoli-Israel,1,3 Gena L Glickman1,4
1Center for Circadian Biology, University of California, San Diego, CA, USA; 2Clinical Investigations Department, Naval Medical Center San Diego, San Diego, CA, USA; 3Department of Psychiatry, University of California, San Diego, CA, USA; 4Department of Psychiatry, Uniformed Services University, Bethesda, MD, USA
Background: Light is the primary synchronizing cue for the circadian timing system, capable of exerting robust physiological effects, even with very dim and/or brief photic exposure. Mammals, including humans, are particularly susceptible to light at night. As such, measures of light in the sleeping environment are critical for evaluating sleep health. Sleep diaries provide inexpensive measures of sleep, but do not typically include light information.
Methods: Four questions probing visual perception of light in the bedtime and waking environments were added to the Consensus Sleep Diary for Morning administration. As part of a lighting intervention study, 18 hospital Labor and Delivery Department personnel completed the sleep diary for 1 week in each of two experimental conditions while wearing Actiwatch devices equipped with photosensors. Diary responses were evaluated against photosensor values from the beginning and end of each rest interval (n=194 rest intervals), as well as against sleep measures, utilizing linear mixed models.
Results: Responses to light questions were related to actual light measures at bedtime, controlling for shift type and experimental condition. In addition, subjective light information at bedtime and waking was related to both objective and subjective sleep parameters, with data generally indicating poorer sleep with light in the sleeping environment.
Conclusion: Questions addressing perception of light in the sleeping environment may provide a crude yet affordable metric of relative photic intensity. Further, as responses relate to sleep outcomes, subjective light information may yield valuable insights regarding mechanisms and outcomes of clinical significance in sleep and circadian research.
Keywords: circadian, actigraphy, photosensor, LAN
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