Warmth Causing Plank Foam Mattress Sag

I’ve been sleeping on a Plank mattress for about six weeks. It was fine until the last week or so, at which time I started to develop back pain due to the mattress being too soft.

When away from the mattress for an hour or so, it feels suitably firm upon return when I test it with my hands and when I lie on it. However, after lying on it for any substantial period, the foam seems to soften substantially. An online search seems to support the idea that warmth from both the room temperature and from body heat tends to soften foam mattresses. This presents something of a challenge for me since, for various reasons, I tend to require a room temperature in the high 70s to be comfortable and to be able to rest.

I’m posting to (a) see if others have faced this issue; and (b) to get suggestions as to how to address this issue. My thoughts so far are to wear warmer bed clothes (long underwear) and lower the room temperature. Plank has a cooling mattress protector that might help.

If anyone has successfully addressed this issue, any input would be appreciated.

Hi voyager39.

Sorry to hear you’re finding some discomfort with your memory foam mattress when the foam heats up and “collapses” as you sleep.

There was someone who, fairly recently…in the last few months I believe…posted to the forum about their troubleshooting with a too soft mattress that they were able to essentially “zone” by adding a support (I believe underneath a specific part of the mattress). Generally speaking, it’s pretty difficult to firm-up a too soft mattress. I’ll try and find it over the next few days!

It may be worth experimenting with wearing warmer clothes to bed to see if the cooler room temperature helps to prevent so much collapsing of the foam, but ultimately I think it’s going to be determined by your body heat (just a guess - I say give it a shot).

Where in your back are you experiencing the pain?


Pain location: the pain is located in two places: (a) the small of my back about 4-5 vertebrae up from my waist; and (b) on the left side of the above location due to sciatica.