Marijuana may offer relief to people who suffer from chronic pain associated with nerve injury, according to a new study.

"This is the first trial to be conducted where patients have been allowed to smoke cannabis [marijuana] at home and to monitor their responses, daily," lead researcher Dr. Mark Ware, clinical research director at the Alan Edwards Pain Management Unit at the McGill University Health Centre in Quebec, said in a statement.

Twenty-three adults with pain caused by injuries to the nervous system, either post-traumatic or post-surgical, were recruited for the study. They were randomly assigned 25 milligram doses of medical marijuana, with varying amounts of THC (the active ingredient in cannabis), ranging from no THC (placebo) to 9.4-percent THC.

They inhaled the marijuana from a pipe three times a day for five days, followed by a washout period of nine days. This cycle was continued four times, and researchers documented on an 11-point scale the patients' mood, sleep and quality of life.

Patients who had the 9.4-percent potency had the greatest reduction in pain and improved sleep, with those taking the lighter potencies reporting less-pronounced effects.

However, scientists need to do further research to determine the efficacy of long-term usage of medical marijuana, as well as the correct quality and dosage.

The research is published in the latest issue of the Canadian Medical Association Journal.