Soft Bed or Hard Bed for Back Pain?

April 3, 2008 -- If Goldilocks had lower back pain, she'd still prefer the bed that was just right.

It's one of the most common questions back pain patients ask. Which is better -- Daddy Bear's hard mattress or Mommy Bear's soft one?

Kim Bergholdt, DC, of Denmark's Funen Back Center, and colleagues tried to find an answer. They randomly assigned 160 patients with lower back pain to sleep in one of three beds for one month.

When the truck pulled up to the patients' houses, it delivered either a hard futon, a water bed (Akva brand), or a body-conforming foam mattress (Tempur brand). Akva and Tempur sponsored the study, although Innovation Futon provided the harder beds.

Unfortunately, many of the patients assigned to the water bed never started the study -- they did not want to sleep on a water bed. And many of the patients assigned to the futon quit the study before it was over.

The large number of dropouts -- and the failure to stratify the patients according to the cause of their back pain -- makes the study hard to interpret, says Robert Molinari, MD, associate professor of orthopaedics at the University of Rochester Medical Center.

Among patients who did finish the study, slightly more preferred the water bed or the body-contour mattress over the hard futon. Even so, there were patients who said they felt better after sleeping on the hard bed as well as patients who said they felt worse after sleeping on the softer beds.

That's no surprise to Molinari.

"We really don't understand why, but some patients respond better to hard mattresses and some to soft ones," Molinari tells WebMD. "There are very few studies lending support to one mattress over another."

So what does Molinari recommend? Exactly the same method Goldilocks used -- trial and error -- to find the bed that's just right.

The Bergholdt study appears in the April 1 issue of the journal Spine.