I brought home a floor model which I felt would do me just fine. Unfortunately I find that by morning sleeping on my back as usual my back and butt are very sore and this has gotten worse over the 3 nights that I have slept. It’s as if I sink through the comfort layer and my butt and back are lying on a board. I have just a thin mattress protector and sheet under me. I cannot return the bed so I am open to other options. By the way I am a man 5’4, 147lbs.
While it’s not as common for back sleepers to have pressure issues with a mattress that has about 3" of memory foam in the comfort layers … based on your description it sounds like your mattress is a little too firm and that the comfort layers may be a little on the thin side for you.
The most likely solution if you are looking to improve pressure relief and soften up your mattress would be to add a topper.
If you are confident that all your mattress needs is a little extra softness and that your “symptoms” are from pressure points or a comfort layer that is too thin for you then post #3 here and the topper guidelines it links to should be helpful. If you prefer the “feel” and response of memory foam over other foam types and since you are in a lighter weight range I would probably consider a softer memory foam topper in the 4 lb range. “Just enough” in terms of thickness is usually less risky so you don’t exchange pressure issues for alignment issues and I wouldn’t go any thicker than a 2" topper. Even 1" could make a difference because back sleepers generally need thinner comfort layers to reduce the risk of their heavier pelvis sinking down too far and causing alignment and lower back issues.
What’s the chance that in a few weeks my body might adjust to this mattress? I had been sleeping on a worn coil prior to this. I really do hurt in the morning and into the afternoon so much so that I slept on the couch last night and awoke feeling much better. I like the feel of the bed when I first lie down. It doesn’t feel like I sink very far. I unzipped a section of the cover and the top layer measures about 2.2". I hope that the support layer is not too dense for me. I keep hearing from the tempurpedic retailers that my body is not used to being in proper alignment and it will take 3 or 4 weeks for my body to adjust. I don’t know if this is just a sales pitch or not. My mattress should already be ‘broken in’ since it is a floor model.
That really depends on the person and on the “muscle memory” they have developed on their previous mattress and on how different a new mattress is from their old one. While your mattress is probably already broken in from being a floor model … it’s not unusual at all that the adjustment period for a new sleeping surface can be 30 - 90 days (although 90 days would be unusual and closer to 30 would be more typical). Post #2 here may also be helpful.