Access to Daylight at Home Improves Circadian Alignment, Sleep, and Mental Health in Healthy Adults: A Crossover Study

Rohan Nagare, May Woo, Piers MacNaughton, Barbara Plitnick, Brandon Tinianov and Mariana Figueiro
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Rohan Nagare: Light and Health Research Center, Department of Population Health, Science and Policy, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
May Woo: View, Inc., Milpitas, CA 95035, USA
Piers MacNaughton: View, Inc., Milpitas, CA 95035, USA
Barbara Plitnick: Light and Health Research Center, Department of Population Health, Science and Policy, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
Brandon Tinianov: View, Inc., Milpitas, CA 95035, USA
Mariana Figueiro: Light and Health Research Center, Department of Population Health, Science and Policy, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA

IJERPH, 2021, vol. 18, issue 19, 1-20

Abstract: As the primary environmental cue for the body’s master biological clock, light–dark patterns are key for circadian alignment and are ultimately fundamental to multiple dimensions of health including sleep and mental health. Although daylight provides the proper qualities of light for promoting circadian alignment, our modern indoor lifestyles offer fewer opportunities for adequate daylight exposure. This field study explores how increasing circadian-effective light in residences affects circadian phase, sleep, vitality, and mental health. In this crossover study, 20 residents spent one week in their apartments with electrochromic glass windows and another week with functionally standard windows with blinds. Calibrated light sensors revealed higher daytime circadian-effective light levels with the electrochromic glass windows, and participants exhibited consistent melatonin onset, a 22-min earlier sleep onset, and higher sleep regularity. In the blinds condition, participants exhibited a 15-min delay in dim light melatonin onset, a delay in subjective vitality throughout the day, and an overall lower positive affect. This study demonstrates the impact of daytime lighting on the physiological, behavioral, and subjective measures of circadian health in a real-world environment and stresses the importance of designing buildings that optimize daylight for human health and wellbeing.

Keywords: daylight; circadian light; lighting for indoor environments; electrochromic glass; blinds; sleep; melatonin; healthy building; circadian alignment; residential lighting (search for similar items in EconPapers)
JEL-codes: I I1 I3 Q Q5 (search for similar items in EconPapers)
Date: 2021
References: View complete reference list from CitEc
Citations: View citations in EconPapers (3)

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