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Cigarette Smoking and Nocturnal Sleep Architecture.
ABSTRACT
Cigarette smoking has been associated with a high prevalence of sleep-related
complaints. However, its effects on sleep architecture have not been fully examined. The primary objective
of this investigation was to assess the impact of cigarette smoking on sleep architecture. Polysomnography
was used to characterize sleep architecture among 6,400 participants of the Sleep Heart Health Study (United
States, 1994-1999). Sleep parameters included total sleep time, latency to sleep onset, sleep efficiency,
and percentage of time in each sleep stage. The study sample consisted of 2,916 never smokers, 2,705 former
smokers, and 779 current smokers. Compared with never smokers, current smokers had a longer initial sleep
latency (5.4 minutes, 95% conf iderice interval (Cl): 2.9, 7.9) and less total sleep time (14.0 minutes,
95% Cl: 6.4, 21.7). Furthermore, relative to never smokers, current smokers also had more stage 1 sleep
(relative proportion = 1.24, 95% Cl: 1.14, 1.33) and less slow wave sleep (relative proportion = 0.86,
95% Cl: 0.78,0.95). Finally, no differences in sleep architecture were noted between former and never smokers.
The results of this study show that cigarette smoking is independently associated with disturbances in sleep
architecture, including a longer latency to sleep onset and a shift toward lighter stages of sleep. Nicotine
in cigarette smoke and acute withdrawal from it may contribute to disturbances in sleep architecture.
Cigarette smoking is a major cause of preventable morbidity and mortality in the
United States(FN1). Although the medical hazards of smoking have been studied for decades, its effects on
sleep generally and on sleep architecture specifically are not well characterized. Cigarette smoking can
alter nocturnal sleep architecture through a number of distinct mechanisms. First, nicotine from cigarette
smoke can stimulate the release of several key neurotransmitters that collectively participate in regulating
the sleep-wake cycle(FN2-5). Second, habitual smokers often experience acute withdrawal as the intake of
nicotine is curtailed during sleep(FN6). Third, the medical consequences associated with cigarette smoking,
such as chronic obstructive lung disease, can disrupt sleep continuity and have a negative impact on sleep
architecture(FN7,8). Epidemiologic investigations indicate that, compared with never smokers, current smokers
experience greater difficulty in initiating and maintaining sleep and are generally more dissatisfied with
their sleep quality(FN9-14). Although subjective assessments of sleep are easily acquired in the context of
large epidemiologic studies, an inherent Imitation is the poor correlation of these assessments with
physiologic recordings of sleep(FN15-18). Research, studies using polysomnographically defined sleep show
that, compared with nonsmokers, current smokers manifest longer latency to sleep onset but otherwise have
comparable sleep architecture(FN19). However, studies using objective sleep data have limited sample sizes
and do not fully account for several confounding factors that can influence sleep architecture, such as age,
alcohol or caffeine consumption, and the presence of medical comorbidity.
The Sleep Heart Health Study (SHHS) is an ongoing, multicenter, longitudinal study
examining the effects of sleep-disordered breathing on the risk of cardiovascular disease(FN20). As part of
the baseline examination, a large cohort of community-dwelling individuals underwent home polysomnography to
assess sleep quality. The availability of objective data on sleep architecture, with self-reported information
on smoking status, provides an opportunity to characterize sleep architecture among current, former, and never
smokers in a large community-based sample. Previous analyses of a subset of the cohort have shown that current
smokers and former smokers, compared with never smokers, have greater amounts of stage 1 and 2 sleep(FN21).
The present study extends these preliminary analyses by examining the associations between cigarette smoking
and sleep architecture while more fully considering potential confounding and using data from the entire SHHS
cohort on a larger repertoire of sleep parameters.
Keywords: nicotine; polysomnography; sleep; sleep stages; smoking; tobacco
