People who take certain prescription sleeping pills even once in a while may be up to five times more susceptible to early death, a U.S. study suggests.

The findings, published in this week's issue of the journal BMJ Open, show the importance of not becoming dependent on sleeping pills to fight insomnia.

In the U.S., an estimated six per cent to 10 per cent of adults used the drugs in 2010.

To look for any associations between use of common hypnotics and increased mortality and cancer risks, the researchers compared death rates among 10,529 people who received prescriptions for sleeping pills and 23,600 others who did not but were similar in terms of age, physical health, income and other factors.

Sleep experts recommend going to bed at the same time all week and avoiding caffeine and TV before bedtime before turning to pills. (Frank Gunn/Canadian Press)

The researchers found that people taking as few as 18 pills a year were 3.6 times more likely to die early than people who take no sleeping pills. Those taking 18 to 132 pills a year were up to five times more likely to die early.

The study was done by Dr. Daniel Kripke of Scripps Clinic Viterbi Family Sleep Centre in La Jolla, Calif., and colleagues.

They concluded that in 2010, hypnotics such as zolpidem, temazepam and eszopiclone may be associated with 320,000 to 507,000 excess deaths in the U.S.

"These pills really seem too dangerous to use," Kripke said in an interview.

A 2010 study based on an analysis of a Statistics Canada database of 14,000 Canadians over 12 years old also concluded that sleeping pills were linked to a similar increase in risk of death, after the researchers controlled for other risk factors.

Safer options

"The meagre benefits of hypnotics, as critically reviewed by groups without financial interest, would not justify substantial risks," the study's authors said. "A consensus is developing that cognitive-behavioural therapy of chronic insomnia may be more successful than hypnotics."

Finding an association between sleeping pills and more deaths does not prove the pills are the cause, but the evidence points in that direction because the risk increased with higher doses, the researchers said.

Dr. Charles Samuels is medical director of the Centre for Sleep & Human Performance in Calgary, and has written guidelines for family doctors on use of sleeping pills. He considers the drugs to be overprescribed, but worries the paper will undermine their appropriate use.

"To globally state that these drugs are killing people is quite frankly irresponsible," Samuels said.

In the study, people on sleeping pills were more likely to have esophageal problems and peptic ulcers.

The subjects were also more likely than cigarette smokers to be diagnosed with lymphomas, lung, colon and prostate cancers.

As for how the early mortality might occur, it's known that people who take sleeping pills may sometimes have residual dizziness the next day that may increase the risk of car collisions or falls.

Sleeping pills also depress the respiratory system, which could reduce the drive to breathe if someone already has sleep apnea, Kabasele said.

Identify source of sleep problem

It's also possible that an increase in depression among people who take sleeping pills could lead to harmful behaviour and suicide.

"There are other options that can help you sleep better before you turn to the pharmaceuticals," said CBC medical specialist Dr. Karl Kabasele.

Kripke said insomnia itself isn't dangerous in terms of mortality, but sleeping pills are.

Sleeping pills are intended for people with acute insomnia, a sleep problem that lasts three weeks or less. But millions of people worldwide take the pills for months, said Dr. Jeffrey Lipsitz, medical director of the Sleep Disorders Centre of Metropolitan Toronto.

People taking sleeping pills should not stop them immediately without the supervision of the doctor who prescribed them because there may be untoward effects of stopping or changing abruptly Lipsitz said.

Sleep experts say it's important to figure out the underlying problem behind insomnia, such as depression, substance use or sleep apnea, and address it by using safer options.

Doctors say everyone could benefit from sleep hygiene — a set of behaviours such as going to bed at the same time all week, avoiding caffeine and stimulation from TV, electronics and strenuous activities before bedtime.

With files from CBC's Kelly Crowe