Working Nights

Smoking and Disturbed Sleep

For a shift worker in need of a good night’s sleep, a relaxing smoke or a soothing cigarette break on the porch is not the answer. Smoking has been linked with less restful sleeping by the American College of Chest Physicians, and a less restful sleep at night is one thing that extended hours workers do not need. Shift workers, especially those on the night shift, already get less sleep than day workers, and this inequity is only compounded since a far greater percentage of shift workers smoke than in the overall population. Suffering from sleep apnea, feeling fatigued at work, complaining about getting a whole four hours of sleep and waking up tired? Don’t let the smoke get in your eyes about solutions.

In February a new study linking smoking with sleep disturbances was reported in the peer-reviewed journal of the American College of Chest Physicians (CHEST Journal). The research shows that cigarette smokers are four times as likely as nonsmokers to report feeling not rested after a night’s sleep. Shift workers, on average, get less sleep compared to regular day workers. And more shift workers smoke; 55% of male and 51% of female shift workers smoke compared to the national average of 25% of men and 21% of women. Smokers tend to report high rates of insomnia; they have a hard time falling asleep and a hard time maintaining sleep.

The study also showed that smokers spend less time in deep sleep and more time in light sleep than nonsmokers, with the greatest differences in sleep patterns seen in the earliest stages of sleep. The researchers speculate that the smokers could be experiencing nicotine withdrawal each night, which may contribute to sleep disturbances. The study author was Naresh M. Punjabi, MD, PhD, FCCP, Johns Hopkins University School of Medicine, Baltimore, MD.

Dr. Punjabi and colleagues from Johns Hopkins compared the sleep architecture of 40 smokers with the sleeping patterns of a matched group of 40 nonsmokers, all of whom underwent home polysomnography (using a polygraph to make a continuous record of multiple physiological variables, such as breathing, heart rate, and muscle activity during sleep).

This study was part of the larger Sleep Heart Health Study, a multi-center study on sleep-disordered breathing and cardiovascular disease. The principal objective of the Sleep Heart Health Study is to determine whether sleep-disordered breathing, including obstructive sleep apnea, is an independent risk factor for the development of cardiovascular and cerebrovascular disease. There are more than 6400 subjects in that larger study. Of these 6,400 subjects, there were only 40 smokers who smoked at least 20 cigarettes a day, had no underlying medical conditions, and met the other criteria. For the study, these subjects were matched with 40 nonsmokers for age, sex, body-mass index, and race.

In previous research studies, it was unclear whether changes in sleep patterns were due to smoking itself or to the medical conditions underlying smoking, such as heart disease or respiratory disease. In this study, smokers with co-existing medical conditions were not allowed to participate. As smoking has been linked with acute and chronic respiratory diseases, coronary heart disease, aneurisms, pneumonia, leukemia, cataracts and cervical, kidney, lung, oral cavity, pancreatic, esophageal, bladder, stomach and ovarian cancer, finding subjects for the study without these other medical conditions was surely difficult (but necessary).

The sleep architecture of the subjects in the study was analyzed using both electroencephalogram (EEG) patterns and power spectral analysis of the EEG, which relies on a mathematical analysis of different frequencies contained within the sleep EEG. These two modes of evaluation provide added strength to the study results. The spectral analysis showed that smokers had a higher percentage of light sleep and a lower percentage of deep sleep. When asked about sleep quality, 22.5 %of smokers reported lack of restful sleep compared with 5.0 %of nonsmokers. The largest difference in sleep architecture occurred at the onset of sleep. This supports the idea that nicotine’s effects are strongest in the early stages of sleep and potentially decrease throughout the sleep cycle.

This study suggests that even when smokers sleep they may be deprived of the much-needed restorative effects of sleep.

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Tags: heart disease, sleep, sleep apnea, smoking, Working Nights