Hello,

I've had a recurring problem with mattresses throughout my life.  In particular, they seem to sink in about a quarter of the way down my spine, and cause back pain and discomfort.  This has affected my posture and quality of sleep, and now I've got a vertebra that protrudes slightly in that area.  I'm looking for a mattress that is least prone to this problem.

Of course, the mattresses I've encountred don't sink in immediately, but it only takes about 1.5 - 2 years for this to happen (I flip and rotate them too; plywood doesn't remedy the problem).  This may be a result of buying mattresses locally and getting ripped off, but I've never really payed attention to the problem until now.

Is the solution a firmer mattress?  Will that be less prone to sinking in?  I really don't have any knowledge of mattresses and I don't trust local merchants, so I'm hoping someone knowledgeable in mattresses can help me out.

Thanks