Insulation under the bed

Never thought about it, but it sure won't hurt anything. Not sure if it will help either, but it definitely won't hurt, so why not give it a try?

I don't think it would make much difference considering there is 6-8 inches of space between the bottom and top of the mattress. I can't imagine losing much body heat to the bottom of the mattress.

Some people do it, specially pop up campers. Keep an eye on it for condensation.

I did it in preparation for a March trip to Alaska. It definitely made a difference.

I used the Owens Corning Pink Foamular panels and covered all of the interior surfaces including the "top" or "ceiling" as it were of the compartment AND the compartment doors. This stuff is water resistant so moisture is not a big factor. I coverd over the insulation with plastic Coroplast panels that are smooth and will Protect the foam insulation.

It is well worth it and it keeps the bed warmer. And yes depending on the temperature you can lose a great deal of body heat through the mattress if it sits on something cold.

Did the same thing. I Have 2x3's supports running on the underside of the bed and I stapled Reflectix to that and sealed the ends with tape to create an air buffer. I used styrofoam panels on the insides of the storage are walls under the bed.

We found ourselves emergency camping out of town in 15* weather for 2 weeks, so this quick trip to Lowe's was well worth the effort.

Reflectex under the mattress and electric dual control mattress heaters!

Yoga / exercise mats are easy to shove into place and are easy to wipe down and put back in place. ... even a heavy wool blanket under the mattress helps quite a bit. After we pulled the old mattress I was surprised at the amount of mold that was on the bottom of the mattress.

Seems the cold causes condensation and the mattress doesn't allow air there so the underside of the mattress can get moldy. I didn't see it until I lifted the mattress completely.

Now my mattress is encased in a mattress cover. Not just one with the elastic corners... I'm talking about the one that goes over the mattress like a pillow case and zips shut.

The moisture/ mold under mattress issue is very common in boat cabins.
To combat the we have lined the top the bed platform on our trailer with a product called Geomat. It is similar to heavy duty air conditioner filter media but more resistant to compaction. Picture a fiber mat about 3/4" thick. It allows air flow under the mattress.

I also did the same thing as Fulltimedaniel using pink foam panels. Made a big difference in the back and was well worth it. In extreme cold I aim a small electric heater under the bed and it makes the back bedroom nice and toasty. We have no problems camping during the winter.

I put that foiled bubble wrap insulation under my mattress and made big difference

Now the mattress slides around easy too!