Taking medications to treat insomnia and anxiety increases mortality risk by 36%, according to a Canadian study.

Genevieve Belleville of the University of Laval's School of Psychology conducted the study, the details of which are published in the latest edition of the Canadian Journal of Psychiatry. The data involves 14,000 Canadians in Statistics Canada's National Population Health Survey and includes information on the social demographics, lifestyle, and health of Canadians age 18 to 102, surveyed every two years between 1994 and 2007.

During this period, respondents who reported having used drugs to treat insomnia or anxiety at least once in the month preceding the survey had a mortality rate of 15.7%, while those not having taken such medications had a rate of 10.5%. After controlling for personal factors that might affect mortality risk, "notably alcohol and tobacco consumption, physical health, physical activity level and the presence or absence of depressive symptoms," Dr Belleville established that the consumption of sleeping pills or anxiety-relieving treatments was associated with a 36% increase in the risk of death.

The study notes that a number of hypotheses have been put forward to explain the link. Sleeping pills and anxiolytics affect reaction time, alertness and coordination "and are thus conducive to falls and other accidents". They may also have "an inhibiting effect on the respiratory system, which could aggravate certain breathing problems during sleep" and these medications "are also central nervous system inhibitors that may affect judgment and thus increase the risk of suicide".

Dr Belleville said that "these medications aren't candy, and taking them is far from harmless". She added that "given that cognitive behavioural therapies have shown good results in treating insomnia and anxiety, doctors should systematically discuss such therapies with their patients as an option".

She concluded by saying that "combining a pharmacological approach in the short term with psychological treatment is a promising strategy for reducing anxiety and promoting sleep".