The Microclimate You Sleep Inside

There is a number on your air conditioner and it is not the temperature you are sleeping at. The reading that decides your night is taken about three millimetres under your shoulder, in a pocket of air sealed above by your own body and below by whatever the bed is made of. It is warmer than the room and wetter than the room, every night, and nothing on the wall controls it.

That pocket has a name in the trade. It is the sleep microclimate, and it behaves almost nothing like the bedroom around it.

Why the room reading misleads you

Singapore's annual mean relative humidity sits close to 84 percent, measured at the Changi station. That is not a seasonal figure, it is the baseline, and an air conditioner does less about it than people assume. It lowers air temperature and condenses out some moisture as a side effect, but a bedroom held at 24 degrees still sits near its dew point for much of the year. The air around you is cold and close to full.

Meanwhile you are producing more of it. A sleeping adult releases moisture steadily through skin and breath across seven or eight hours, and a good share of that goes downward rather than up. So the useful question was never how cold the room can be made. It is whether the moisture has anywhere to go once it arrives at the surface underneath you.

Three of its four walls are you.

The one wall you get to choose

The pocket is bounded above and at the sides by your body and the bedding draped over it, and you are not going to change those. The floor of it is the mattress, and that is the only surface in the whole arrangement you actually specify, or re-specify later without replacing the bed.

Most synthetic foam makes a poor floor for it. The cell walls are largely sealed, so air and moisture travel around the material rather than through it. Heat gathers at the point of contact and the vapour has no exit, which is the mechanism behind waking damp in a tropical bedroom. No thermostat setting corrects it, because the problem is underneath you rather than around you.

Latex has an open structure: interconnected pockets that let air pass through the body of the material. Dampness that reaches the surface has somewhere to travel rather than sitting where it landed. The Mattress works that in two further ways. The taupe bamboo casing takes moisture off the skin at the point of contact, and airflow channels sit hidden at the shoulders, the zone carrying the most concentrated load and the first place the material would otherwise be pressed shut. It is built without adhesive, which matters here for a reason set out in the argument for natural materials in a tropical bedroom: a cured glue line is a vapour barrier, and there is one at every level of an ordinary stack.

What it feels like when the floor of it works

Not cold. That is worth saying plainly, because cold is what gets sold and it is not what happens. What happens is that the pocket stops filling up. The surface under your shoulder is dry at four in the morning instead of faintly damp, so you do not surface, roll to the cool side and start the whole approach to sleep again.

Most of the effort spent on sleeping well in this climate goes into the room: the setting, the fan, the curtains, the dehumidifier in the corner. The room is the easy part to adjust and the part with the least contact with you. The few millimetres against your skin get almost no attention at all, and they are the only climate you are actually in.

Explore The Mattress, or the reasoning behind the build.