Why an open window will help you sleep

IF you struggle to get a good night’s sleep, think about opening your bedroom window or door.

It helps the air circulate at night, leading to better quality sleep, a study found.

Sleepers were less likely to toss and turn and wake up, researchers said.

Scientists believe that poor ventilation leads to a build-up of carbon dioxide in the bedroom as a result of respiration.

To test the effect of keeping a window open, researchers tracked the sleep of 17 healthy students. They slept with windows or doors either open or shut, and the room temperature was monitored.

There was also a motion sensor in the pillow and one attached to the sleepers’ arm.

Levels of CO2 were measured in the bedrooms over five days for the study published in the journal Indoor Air.

The subjects, based in Eindhoven in the Netherlands, filled in questionnaires and kept sleep diaries during the study.

The authors concluded: ‘Lower CO2 levels implied better sleep depth, sleep efficiency, and lesser number of awakenings.’

With a window or door closed, the average CO2 level was 1150 parts per million, compared with 717 ppm when the window or door was open.

Humidity levels were similar in both conditions as were temperatures – with the authors reporting that subjects sleeping in cooler conditions adjusted their clothing accordingly. The findings showed an open window was better for reducing CO2 than an open door. However, an open door may be preferable if it is noisy outside.

A previous study by a different team at the Copenhagen School of Design and Technology found similar results. They said: ‘The perceived freshness of bedroom air improved significantly when the CO2 level was lower, as did next-day reported sleepiness and ability to concentrate’.