Second-Hand Smoke Adds to Sleep Woes of Pregnancy

TOKYO, Sept. 4 -- Second-hand cigarette smoke can exacerbate the sleep disturbances of pregnant women, investigators here found in two surveys of nearly 36,000 women.

Non-smokers exposed to passive tobacco smoke had an occurrence rate of common sleep disturbances midway between that of pregnant smokers and non-smokers who avoided passive smoke, reported Takashi Ohida, M.D., of Nihon University in Tokyo, and colleagues, in the September issue of Sleep.

"The relationship between passive smoking exposure and some negative health outcomes in pregnant women could therefore be mediated by the ability of passing smoke to disrupt sleep," they wrote.

They recommended educating patients about the adverse effects of passive smoking during pregnancy, including the exacerbation of problems with sleep hygiene.

The authors reviewed results of two studies sent to patients at maternity facilities throughout Japan in 2002 and in 2006. The patients were asked whether they were current smokers, their exposures to environmental smoke, sleep status, and demographic information.

The questionnaires included questions about sleep status during the previous month, asking whether the patients had subjective insufficient sleep, difficulty in initiating sleep, difficulty maintaining sleep, early-morning awakening, short sleep duration, excessive daytime sleepiness, and loud snoring or uncomfortable breathing causing nocturnal awakening (the latter was included only in the 2006 survey).

There were a total of 16,396 respondents to the 2002 survey and 19,386 to the 2006 iteration.

The authors found that 9.9% of pregnant women in the 2002 survey smoked during their pregnancies, compared with 7.8% in 2006. Environmental smoke exposure also decline between surveys, from 62.1% of pregnant women in 2002, to 52.7% in 2006. In both studies, husbands were the primary source of exposure for 80% or more of the women.

Active smokers had the highest prevalence of all six sleep-disturbance items on the 2002 questionnaire, and all seven such items on the 2006 version.

"The prevalence of each sleep-related item among nonsmokers with environmental tobacco smoke (passive smoking) showed a mean value intermediate between that among active smokers (smoking) and that among nonsmokers without environmental tobacco smoke (non-smoking)," the investigators wrote.

When the investigators conducted multiple logistic regression analyses to estimate the association between sleep disorders and smoking status after adjusting for covariates, they found that in the 2002 survey, non-smokers exposed to passive smoke were significantly more likely than those not exposed to passive smoke to report insufficient amounts of sleep, difficulties in initiating sleep, and short sleep duration.

Non-smoking passive smokers in the 2006 survey were significantly more likely to suffer from subjective insufficient sleep, difficulty initiating sleep, early morning awakening), short sleep duration, and snoring loudly or breathing uncomfortably.

In both surveys, those women who were surrounded by family and friends who smoked were significantly more likely to experience all of the disturbances listed above, except for loud snoring/uncomfortable breathing, the authors reported.

They acknowledged that their study was limited by its cross-sectional design; reliance on self-report of sleep, alcohol and smoking; uncertainties about the truthfulness of responders, and the lack of questionnaire items on caffeine consumption or other factors that might have affected sleep quality.