Elsevier

Building and Environment

Volume 132, 15 March 2018, Pages 11-20
Building and Environment

A review of the environmental parameters necessary for an optimal sleep environment

https://doi.org/10.1016/j.buildenv.2018.01.020Get rights and content

Abstract

An appropriate sleep environment is critical to achieve adequate quality and quantity of sleep. General sleep hygiene recommendations suggest that individuals should maintain a cool, dark, quiet sleep environment. Our goal was to conduct a review of the evidence surrounding the optimal characteristics for the sleep environment in the categories of noise, temperature, lighting, and air quality in order to provide specific recommendations for each of these components. We found that all forms of noise in the sleep environment should be reduced to below 35 dB. The optimal ambient temperature varies based on humidity and the bedding microclimate, ranging between 17 and 28 °C at 40–60% relative humidity. Complete darkness is optimal for sleep and blue light should be avoided during the sleep opportunity. Sea level air quality, with ventilation is optimal for sleep and supplemental oxygen is a useful countermeasure for improving sleep quality at altitude. Architectural design that incorporates these elements into bedroom design may improve sleep quality among inhabitants of such environments.

Introduction

Achieving sleep of adequate quality and quantity is dependent on an individual having enough time available for sleep at an appropriate circadian phase, with general adherence to basic sleep hygiene recommendations, including sleeping in an environment that is conducive to sleep. Recent consensus reports on sleep need support the notion that adults require 7–9 h of sleep per night [33,117], and studies of sleep and circadian rhythms support the importance of regular sleep timing in positive sleep outcomes [29,100]. Although environmental sleep disrupters are recognized as a contributor to some sleep disorders, the empirical evidence supporting the recommendations on what constitutes an appropriate sleep environment are dispersed over many studies. In addition, there are few resources available to architects and engineers that provide explicit guidance on what characteristics are necessary for designing the optimal bedroom environment. An inappropriate sleep environment can lead to disrupted sleep and reduced sleep quality even in the absence of sleep disorders and when sleep is timed to provide for an optimal sleep opportunity. The goal of this review was to identify the impact of environmental factors on sleep, including ambient noise, temperature, light, and air quality, in order to guide the design of bedroom spaces optimized for healthy sleep.

Section snippets

Methods

We conducted a literature search to identify research papers describing sleep outcomes for the environmental parameters of interest. Given the prevalence of homographs within the search terms of interest (e.g. the terms “light” and “sleep” returned numerous results on “light sleep”), we took a three-tiered approach to include the widest range of literature. We conducted a primary search in PubMed using keywords relevant to each environmental parameter (described below). We conducted a screen of

Noise

Exposure to noise can disrupt sleep quality and quantity [61]. The magnitude of sleep disruption conferred by noise depends on the decibel level (dB), the frequency and pitch, duration (i.e. continuous, intermittent, or impulsive) and whether the noise is meaningful (e.g. a familiar voice). A World Health Organization working group report on noise determined that there is a causal relationship between nighttime noise exposure and self-reported sleep disturbances, use of pharmaceuticals,

Ambient temperature

The relationship between endogenous core body temperature, skin temperature, ambient temperature, airflow and humidity, clothing, and insulation of bedding must all be taken into account when evaluating the impact of temperature on sleep (Fig. 1). Under normal conditions, the circadian rhythm of core body temperature declines just prior to the time of optimal sleep onset and continues to decline throughout the sleep episode, reaching a nadir at approximately 6 h after sleep onset [25,48].

Light

Light leads to sleep disruption due to two factors; first, light resets the circadian pacemaker, leading to a shift in the timing of circadian phase relative to the scheduled sleep episode. Second, light is an environmental stimulus that can cause sleep disruption and night waking. The circadian rhythm is reset by exposure to light through the eyes [22,23,123]. Inappropriately timed light exposure is capable of inhibiting sleep onset and leading to shifts in circadian phase that can impact

Air quality

Poor air quality or gaseous air mixtures that deviate from typical Earth-based sea level air mixtures are capable of causing sleep disruption and impaired breathing during sleep. Exposure to reduced levels of O2 and elevated levels of CO2 can lead to sleep disruption. Ventilatory responses to hypercapnia have been shown to be lower during sleep than during wake [57,91] and a mean value of 3.8% (range 2.3–6.5%) end-tidal CO2 partial pressure has been shown to cause awakening from sleep [30].

Conclusions and research gaps

Sleep is critical to health and daytime functioning. In order for individuals to achieve optimal sleep, they must have access to a sleep environment that allows them to achieve quality sleep, free of external disruption. We found that the optimal sleep environment should be insulated to attenuate intermittent noise, in particular noises above 35 dB. Some evidence suggests that continuous noise may be useful in situations where intermittent noise cannot be eliminated or reduced. More research is

Limitations

Due to the breadth of research on sleep related outcomes, interactions between sleep quality and various special populations were not considered in this review. It is possible that individuals with sleep disorders, for example, may benefit from different environmental conditions than the ones described in the current review. Additionally, although a systematic effort was undertaken to include all relevant articles pertaining to this review, it is possible that some articles were missed in this

Acknowledgements

This study was funded by the Human Research Program at NASA Johnson Space Center (BHP-ARC ITA 14643). The authors wish to thank Lisa Sewall for assistance with obtaining publications for this report, as well as Dr. Durand Begault, and Dr. Brian Smith for providing helpful comments to this review. The authors also wish to thank Renna Bushko, Ravi Chachad, Ann Marie Davidson, Maricruz Esparza, Cindy Hu, Rohit Rao, and Vanessa Real for assistance in collecting literature associated with this

References (128)

  • L. Lan et al.

    Experimental study on thermal comfort of sleeping people at different air temperatures

    Build. Environ.

    (2014)
  • A.M. Luks et al.

    Room oxygen enrichment improves sleep and subsequent day-time performance at high altitude

    Respir. Physiol.

    (1998)
  • A. Muzet

    Environmental noise, sleep and health

    Sleep Med. Rev.

    (2007)
  • K. Okamoto-Mizuno et al.

    Effects of partial humid heat exposure during different segments of sleep on human sleep stages and body temperature

    Physiol. Behav.

    (2005)
  • S. Pirrera et al.

    Field study on the impact of nocturnal road traffic noise on sleep: the importance of in- and outdoor noise assessment, the bedroom location and nighttime noise disturbances

    Sci. Total Environ.

    (2014)
  • R. Plywaczewski et al.

    Sleep structure and periodic breathing in Tibetans and Han at simulated altitude of 5000 m

    Respir. Physiol. Neurobiol.

    (2003)
  • M. Reite et al.

    Sleep physiology at high altitude

    Electroencephalogr. Clin. Neurophysiol.

    (1975)
  • M. Saremi et al.

    Effects of nocturnal railway noise on sleep fragmentation in young and middle-aged subjects as a function of type of train and sound level

    Int. J. Psychophysiol.

    (2008)
  • İ. Altun et al.

    The contributing factors to poor sleep experiences in according to the university students: a cross-sectional study

    J. Res. Med. Sci.

    (2012)
  • V. Bach

    Effect of continuous heat exposure on sleep during partial sleep deprivation

    Sleep

    (1994)
  • I.A. Barash et al.

    Nocturnal oxygen enrichment of room air at 3800 meter altitude improves sleep architecture

    High Alt. Med. Biol.

    (2001)
  • M. Basner et al.

    Single and combined effects of air, road, and rail traffic noise on sleep and recuperation

    Sleep

    (2011)
  • M. Basner et al.

    Aircraft noise effects on sleep: application of the results of a large polysomnographic field study

    J. Acoust. Soc. Am.

    (2006)
  • A. Baughman et al.

    Indoor humidity and human health–Part I: literature review of health effects of humidity-influenced indoor pollutants

    Cent. Built. Environ.

    (1996)
  • G.L.T. Beko et al.

    Ventilation rates in the bedrooms of 500 Danish children

    Build. Environ.

    (2010)
  • T. Bodin et al.

    Annoyance, sleep and concentration problems due to combined traffic noise and the benefit of quiet side

    Int. J. Environ. Res. Publ. Health

    (2015)
  • M.H. Bonnet

    Effect of sleep disruption on sleep, performance, and mood

    Sleep

    (1985)
  • G.C. Brainard

    Action spectrum for melatonin regulation in humans: evidence for a novel circadian photoreceptor

    J. Neurosci.

    (2001)
  • G.C. Brainard

    Sensitivity of the human circadian system to short-wavelength (420-nm) light

    J. Biol. Rhythm.

    (2008)
  • D. Bruck et al.

    How does the pitch and pattern of a signal affect auditory arousal thresholds?

    J. Sleep Res.

    (2009)
  • H.J. Burgess et al.

    Home lighting before usual bedtime impacts circadian timing: a field study

    Photochem. Photobiol.

    (2014)
  • A.M. Chang et al.

    Evening use of light-emitting eReaders negatively affects sleep, circadian timing, and next-morning alertness

    Proc. Natl. Acad. Sci. U. S. A.

    (2015)
  • C.H. Cho

    Exposure to dim artificial light at night increases REM sleep and awakenings in humans

    Chronobiol. Int.

    (2016)
  • J.H. Coote et al.

    Respiratory changes and structure of sleep in young high-altitude dwellers in the Andes of Peru

    Eur. J. Appl. Physiol. Occup. Physiol.

    (1993)
  • C.A. Czeisler et al.

    Use of bright light to treat maladaptation to night shift work and circadian rhythm sleep disorders

    J. Sleep Res.

    (1995)
  • C.A. Czeisler et al.

    Sleep and circadian rhythms in humans

    Cold Spring Harbor Symp. Quant. Biol.

    (2007)
  • V. de Aquino Lemos et al.

    High altitude exposure impairs sleep patterns, mood, and cognitive functions

    Psychophysiology

    (2012)
  • D.-J. Dijk et al.

    Invited Review: integration of human sleep-wake regulation and circadian rhythmicity

    J. Appl. Physiol.

    (2002)
  • A. Fletcher et al.

    Sleeping with an electric blanket: effects on core temperature, sleep, and melatonin in young adults

    Sleep

    (1999)
  • E.E. Flynn-Evans et al.

    Circadian misalignment affects sleep and medication use before and during spaceflight

    npj Microgravity

    (2016)
  • B. Gothe et al.

    Effect of quiet sleep on resting and CO2-stimulated breathing in humans

    J. Appl. Physiol.

    (1981)
  • M.A. Grandner et al.

    Short wavelength light administered just prior to waking: a pilot study

    Biol. Rhythm. Res.

    (2013)
  • J.B. Holt et al.

    Airport noise and self-reported sleep insufficiency, United States, 2008 and 2009

    Prev. Chronic Dis.

    (2015)
  • M. Hoshikawa et al.

    Changes in sleep quality of athletes under normobaric hypoxia equivalent to 2,000-m altitude: a polysomnographic study

    J. Appl. Physiol.

    (2007)
  • L. Jalali et al.

    Before-after field study of effects of wind turbine noise on polysomnographic sleep parameters

    Noise Health

    (2016)
  • C. Janson

    Insomnia is more common among subjects living in damp buildings

    Occup. Environ. Med.

    (2005)
  • P.L. Johnson et al.

    Sleep architecture changes during a trek from 1400 to 5000 m in the Nepal Himalaya

    J. Sleep Res.

    (2010)
  • I. Karacan et al.

    Effects of high ambient temperature on sleep in young men

    Aviat Space Environ. Med.

    (1978)
  • T. Kawada et al.

    Instantaneous change in transient shift of sleep stage in response to passing truck noise

    Environ. Health Prev. Med.

    (1998)
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