When you move in your mattress the shifting and jostling that causes you or your wife to awaken can be eliminated in several ways. I will tackle what you believe to be the problem.

First the bed needs to be steadied. Until you control the shaking and trembling of the bed frame, even the best memory foam mattress will not reduce the movement you both are feeling. A frame with feet and stout center supports can add needed strength and stability to your headboard and bed frame. If you have a headboard and footboard and the down hooks are loose, simple shims are made to eliminate the motion.

Here are some mattress options that can stop the bothersome and annoying of bed movement between the 2 of you.

1. Memory Foam Mattress
http://www.stlbeds.com/mattresses/memory-foam/
2. A Mattress With Fabric Encased Coils that are not connected to one another.
Our Tension Ease Collection from Englander which includes the Milan Firm Milan Plush and Milan Pillow Top http://www.stlbeds.com/mattresses/spring/#tension

You can look at the Deep Sleep, Heirloom, Nightfall, and the Soft Touch. You can see those mattresses at
http://www.stlbeds.com/mattresses/spring/#campbell

Really any dual mattress that divides in the middle will also eliminate movement as well. Examples: some mattress and boxsprings, airbeds, softside waterbeds, all natural latex rubber mattresses etc.

Sometimes there can be memory foam heat issues with those who always sleep hot especially in the case of women going through the change of life. Understand this, heat trouble can be a concern with any foam mattress or mattress and box spring for that matter that has not planned good breatheability into a beds design.

This is a great question for the dealers you visit when you shop for memory foam beds. If you happen to be in the St. Louis Metro area please contact me. I would be glad to explain the various models and problems if we had any. If you are not satisfied with that answer you may want to look into all rubber latex mattresses as an alternative.