Woman lying in bed with bare back trying to sleep on a hot night on a hot mattress

Helpful mattress articles

Why is my mattress hot?

OK, here’s the hard, cold truth about mattresses: they hold onto your body heat and they can get hot. Whilst some are definitely worse than others, the main culprit in the heat-holding department is foam, something that every mattress has.

Foam is made up of billions of open, multi-dimensional cells with rubber-like walls that capture and hold a sleeper’s body heat.

The more dense the foam (generally latex and visco elastic or memory foam), the more heat that the foam will retain. You shouldn’t let this stop you from buying a mattress which utilises these foams, as these are the best foams for comfort and longevity of comfort in a mattress.

Our bodies are running at a constant temperature of around 37°c degrees. That’s pretty hot.

You just need to make some simple changes to your sleeping environment. We know that mattresses, like woolly jumpers don’t generate their own heat – it’s our bodies that are running at a constant temperature of around 37°c degrees. That’s pretty hot. If your body heat can escape from areas of your body that are not in contact with the mattress then heat will not build up in the first place.

To avoid ever waking up in a hot, sweaty mess, follow these easy steps:

Don’t buy a solid foam mattress

Once again, it’s foam that holds heat so a solid foam bed will be the worst choice for holding heat. A mattress that uses an innerspring unit for support is the best choice as the open spring unit won’t hold heat and will allow body heat to disperse away from you. Airflow throughout the mattress is another bonus that you get from an innerspring, so the mattress will be less likely to hold all sorts of nasties like dust mites and mould (this is a genuine problem for solid foam mattresses in warm climates).

Ditch the doona

Just like a mattress holds your body heat, so does a doona or quilt. Usually a doona consists of polyester fibre and just like polyester clothing, your skin will struggle to breathe underneath it and your body heat will not be able to disperse. Even doonas with a pure wool filling will hold a lot of heat, just like a pure wool jumper does. When you wake up because you’re overheating, you tend to kick the doona off so that the top part of your body can cool down quickly. Of course, the underside of your body won’t, so the poor mattress gets the blame.  But your best bet is to not to let the body heat build-up in the first place. Use lighter layers of bedding in natural fabrics so that any excess heat can disperse through these as you sleep. A good choice for bedding would be quality cotton sheets with a thread count of 300-400 (Google why the old-1000-thread-count story is a bogus one) and light, pure wool blankets or thin quilts filled with a cotton wadding.

Don’t use plastic mattress protectors

We always recommend a good mattress protector to prolong the life of your mattress but that doesn’t extend to those awful, cheap, plastic sheets that market themselves as waterproof. Instead, opt for a quality cotton mattress protector.

Wear light sleepwear or none at all

You have a golden opportunity every night to let your skin breathe, you may as well take advantage of it.

Cool down your bedroom

Today’s homes aren’t always well insulated, and our bedrooms are built on the outer perimeters of the house so that we can have bedroom windows. Unfortunately, that means your bedroom might just be one of the warmest rooms in the home and your mattress will be soaking up that warmth all day. Cool the room for at least half an hour before you go to bed with a blast of air conditioning or by opening the windows to allow the heat in the room to escape. Also, don’t position your bed up against the external walls of the room (usually the hottest walls as they are exposed to the outside temperature). You’re better off to sleep next to an internal wall which will naturally be cooler.

Buy a firmer mattress

If you’re a really hot sleeper and the steps above still don’t fix the issue, then you may be better off with a firmer style of mattress. That’s not to say that you need a mattress that feels like a rock but simply one that uses less foam in the comfort layers. There are many good mattresses on the market that utilise a softer spring, so even with less filling in the comfort layers, you’ll still get a comfortable and conforming mattress. As mentioned earlier, innerspring units are far superior to a foam core for allowing air flow through the mattress and for dispersing body heat. Our Firm But Fair mattress has firmer foams so that you feel that you’re sleeping more on top of the mattress, instead of in it.