Taking sleeping pills or medication for anxiety is linked to an increased risk of death, according to a study by a University of Laval researcher in Quebec City.

Psychologist Geneviève Belleville found a rise of 36 per cent in the mortality rate among Canadians who reported having used anxiolytic and hypnotic medication to treat insomnia or anxiety at least once in the previous month.

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"These medications aren't candy, and taking them is far from harmless," Belleville said in a release.

Her study was published in the current issue of the Canadian Journal of Psychiatry.

The data comes from Statistics Canada's National Population Health Survey, which reports 12 years worth of information on more than 14,000 Canadians between the ages of 18 and 102. The survey was conducted every two years between 1994 and 2007.

Belleville's analysis of that data showed those who took medications had a mortality rate of nearly 16 per cent, while those who reported not having used such medications had a rate of nearly 11 per cent.

After controlling for factors that might affect mortality risk — such as alcohol and tobacco use, physical health, physical activity level, and depression —Belleville found sleeping pills or anxiety-relieving drugs were linked to a 36 per cent increase in the risk of death.

The results may have to do with the fact such medications affect reaction time, alertness and co-ordination. People who take them may be more likely to fall or have another accident.

The drugs may also inhibit the respiratory system, which could worsen breathing problems during sleep. In addition, the drugs are central nervous system inhibitors and may affect judgment, perhaps increasing the risk of suicide.