Once upon a time, long before mass production, chemical companies and the Industrial Revolution, people lived off the land. You watch a western and the cowboys have their bed roll, pull up a rock for their pillow, and fall asleep. There is evidence that people in Egypt thousands of years ago made mattresses with layers of grasses and fur, and it is likely not too far a stretch to imagine that cavemen slept on layers of animal pelts and fur. The commercial mattress, in the course of history, is a relatively new invention. 

I have people in the store all the time tell me their doctor or chiropractor told them to get the firmest bed they can find. A lot of people also site their parents or grandparents as well, echoing the same advice. Despite cowboys sleeping on the prairie and cavemen sleeping on pelts, is this firm advice the best advice?

First of all, what I find is that most people confuse "firm" with "support". Hard and Supportive are not the same thing. If hard or firm were the best, we would all be sleeping comfortably on the floor. And while there is a small segment of the population who can sleep like that, the majority of us cannot. 

Proper support comes from a surface that supports the curvature of the spine while not putting too much pressure on the body. A good memory foam mattress like the memory foam mattresses at Nest Bedding in Berkeley, San Francisco and Mountain View. You can find firm, medium and soft memory foam mattresses that will all support the spine properly while giving you the comfort you desire. Support in a memory foam mattress comes from density: that means the foam is dense and will not let you sink too much while absorbing pressure instead of creating it. Metal spring or coil mattresses create pressure, which in turn leads to disturbed sleep. Your body has to constantly adjust to relieve the pressure. Very dense memory foam mattresses also can cause this issue if the foam is so dense that it does not yield and causes heat to build up. Tempurpedic mattresses have this complaint frequently.

A good quality, breathable memory foam mattress can provide support and comfort without putting your body on a surface that hurts your body and cuts off blood flow. My professional recommendation is a supportive foam mattress, not a metal coil one, and a surface you find comfortable AND supportive.