Window open or closed: what is the sleep efficiency?
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January 12, 2016

Window open or closed: what is the sleep efficiency?

Laverge et al. (2012) asked 22 students to sleep in their dormitory room either with the window open (high ventilation rate) or with the window closed (low ventilation rate). CO2 concentration, air temperature, and relative humidity were measured throughout. Sleep duration and quality were assessed using actigraphy, and the subjects completed a questionnaire every morning to report their sleep quality. Sleep efficiency (proportion of time in bed spent asleep) tended to be less when windows were open, which is an unexpected result, but neither this nor any other effect of the intervention on the actigraphy data reached significance and as subjects were aware that the window was open, the reported effects on subjectively perceived sleep quality could have been due to expectation. In laboratory experiments in which a small flow of outdoor air was supplied directly to the breathing zone (personal ventilation), Lan et al. (2013) found that this reduced the time it took elderly subjects to fall asleep, and Zhou et al. (2014) found that heart-rate variability during sleep was reduced, from which they concluded that subjects slept more soundly. In their review of the literature on IAQ effects on sleep, Urlaub et al. (2015) concluded that no other studies of IAQ effects on sleep had been reported.

Read an interesting article by P. Strøm-Tejsen, D. Zukowska, P. Wargocki, and D. P. Wyon published in the Journal of INDOOR AIR, doi:10.1111/ina.12254. The article reports two field intervention experiments on how the effective ventilation rate in bedrooms affects sleep and next day performance.

The effects of bedroom air quality on sleep and next-day performance (link here).