Smokers may get fewer hours of sleep - and poorer quality sleep - than non-smokers, a new study suggests.
Of nearly 1 100 smokers surveyed by German researchers, 17% got less than six hours of sleep each night and 28% reported "disturbed" sleep quality. That compared with rates of 7% and 19%, respectively, among more than 1 200 non-smokers.
The findings cannot prove that smoking directly impairs sleep. Smokers may have other habits that could affect their sleep - such as staying up late to watch TV or getting little exercise, said lead researcher Dr Stefan Cohrs, of Charite Berlin medical school in Germany.
But there is also reason to believe smoking is to blame - namely, the stimulating effects of nicotine, he told Reuters Health in an email. There have also been studies showing that smokers' sleep improves after they quit the habit, according to Dr Cohrs.
Study included smokers and non-smokers
The new study, which appeared in Addiction Biology, included 1 071 smokers and 1 243 non-smokers who were free of mental health disorders - since those conditions may make a person both more likely to smoke and more vulnerable to sleep problems.
The researchers used a standard questionnaire that gauges sleep quality. Overall, more than one-quarter of smokers had a score that landed them in the category of "disturbed" sleep. That means they had a "high probability" of having insomnia, according to Dr Cohrs.
Many things can affect sleep quality. Dr Cohrs' team was able to account for some of those factors, like age, weight and alcohol abuse. And smoking was still linked to poorer sleep quality. It's still possible there are other things about smokers that impair their sleep. But Dr Cohrs thinks the most likely culprit is nicotine.
Of course, there are already plenty of established reasons to kick the smoking habit. But the prospect of better sleep could offer people more motivation, he noted.
(Reuters Health, Amy Norton, September 2012)
What's in that cigarette?
A to Zzz of sleep
Non-smokers: know your rights