METHODS

Design:

randomised controlled trial.

Allocation:

concealed.*

Blinding:

{patients, clinicians, data collectors, outcome assessors, data analysts, and monitoring committee}†.*

Follow up period:

90 days.

Setting:

Spain.

Patients:

313 adults who were ⩾18 years of age (73% women), had ⩾3 months of chronic low back pain, and had pain while lying in bed or on rising. Exclusion criteria: referred pain; habitual prostration; possible systemic disease, inflammatory disease, or cancer; diagnosis or suspicion of fibromyalgia; pregnancy; habitually sleeping in a different bed ⩾2 nights/week; use of anti-inflammatory medication with a 24 hour …