This is our standard: what we derive from the sources for a bedroom. These are not medical limits, and a room that meets them doesn't promise better sleep. It removes what can get in the way of sleep.
01
Light
The standard: Dimmed, warm light in the evening; as dark as possible at night.
Why: Gooley and colleagues (2011) compared ordinary room light, below 200 lux, with dim light below 3 lux in the hours before sleep. In room light, melatonin production started later and lasted around 90 minutes less. Wright and colleagues (2013) showed that the rhythm of people who went camping for a week, without electric light, shifted towards the sun.
What we measure: Light levels in the evening and at night, and the light that comes in from outside.
More on this in the knowledge base →02
Sound
The standard: Outside, an average of no more than 40 dB at night; inside, as quiet as possible, without peaks.
Why: In its Night Noise Guidelines for Europe (2009), the WHO names an annual average of 40 dB outside at night as the target, and 55 dB as an interim target where that is not yet achievable. For the room itself, what an average doesn't show matters too: individual peaks from traffic, building services or neighbours.
What we measure: The sound level across the night, the average and the peaks.
More on this in the knowledge base →03
Temperature
The standard: Cool, and cooler than the rest of the house.
Why: Okamoto-Mizuno and Mizuno (2012) reviewed the research on heat and sleep: in a warm environment people lie awake longer and get less deep sleep and dream sleep, especially when the air is humid as well. Exactly how cool differs by person, by season and by duvet.
What we measure: How the temperature changes across the night, and how quickly the room warms up.
More on this in the knowledge base →04
Humidity
The standard: A relative humidity between 40 and 60 per cent.
Why: Arundel and colleagues (1986) concluded that within a relative humidity of 40 to 60 per cent, most of the adverse effects of air that is too dry or too humid are at their smallest, from dust mites and mould to dry mucous membranes.
What we measure: The relative humidity, all week, day and night.
More on this in the knowledge base →05
Fresh air
The standard: Ventilated, even with the door closed: keep CO₂ low.
Why: Strøm-Tejsen and colleagues (2016) had students sleep for one week with and one week without extra ventilation. With ventilation, CO₂ averaged around 835 ppm; without, around 2,395 ppm. With ventilation, sleep was more efficient, measured with a wrist monitor, and they performed better the next day. CO₂ itself is mainly a measure of how fresh the air is.
What we measure: CO₂ across the night, with the door and windows as you usually have them.
06
The bed
The standard: A bed that suits your body, your sleeping position and your partner, tried first.
Why: Of the six factors, this is the only one you touch all night long. Firmness, topper and size make the difference, and you choose them best after a full night rather than ten minutes in a shop. Hästens recommends 210 by 210 centimetres as the standard size.
What we measure: How you lie, what you have now, and which firmness and size you would like to try.