Light Levels in ICU Patient Rooms: Dimming of Daytime Light in Occupied Rooms

Elizabeth R. Lusczek, Melissa P. Knauert

Research output: Contribution to journalArticlepeer-review

8 Scopus citations


One-third of patients report disruption of sleep by overnight light. Importantly, light causes both immediate sleep disturbance and influences circadian function, a fundamental process underpinning high-quality sleep. Short bursts of light at night and/or lack of bright daytime light disrupt circadian alignment, leading to sleep deficiency. To improve understanding of 24-hour light patterns, we conducted a longitudinal study of light levels in intensive care unit (ICU) rooms. Over 450 room-days, we observed high variability, dim daytime light, and active dimming of natural sunlight in occupied rooms. Such noncircadian light patterns have multifactorial influences on sleep and are a key target for sleep improvement in the ICU.

Original languageEnglish (US)
JournalJournal of Patient Experience
StatePublished - Jul 23 2021

Bibliographical note

Funding Information:
The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: Dr. Knauert was supported by the National Center for Advancing Translational Science (KL2 TR000140) to conduct this project. Dr. Knauert is currently supported by the NHLBI (K23 HL138229) and the American Academy of Sleep Medicine Foundation.

Publisher Copyright:
© The Author(s) 2021.


  • circadian
  • critical illness
  • intensive care unit
  • light
  • lux
  • sleep
  • sleep deficiency
  • sunlight


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