Aug. 30, 2010 -- Three puffs a day of cannabis, better known as marijuana, helps people with chronic nerve pain due to injury or surgery feel less pain and sleep better, a Canadian team has found.

''It's been known anecdotally," says researcher Mark Ware, MD, assistant professor of anesthesia and family medicine at McGill University in Montreal. "About 10% to 15% of patients attending a chronic pain clinic use cannabis as part of their pain [control] strategy," he tells WebMD.

But Ware's study is more scientific -- a clinical trial in which his team compared placebo with three different doses of cannabis. The research is published in CMAJ, the Canadian Medical Association Journal.

The new study ''adds to the trickle of evidence that cannabis may help some of the patients who are struggling [with pain] at present," Henry McQuay, DM, an emeritus fellow at Balliol College, Oxford University, England, writes in a commentary accompanying the study.