Large survey studies suggest that smokers experience, on average, poorer sleep quality relative to non-smokers. Despite this, there are few well-designed studies that have systematically examined sleep profiles of smokers. Nicotine interacts with several neurotransmitters in the brain – notably dopamine – and could potentially have adverse effects on specific sleep stages.
In a recent study, published online in the journal Sleep Medicine, researchers from Germany compared smokers with non-smokers in terms of objective and subjective sleep. The study team recruited individuals who were free from psychiatric or medical illness and asked them to sleep in a sleep laboratory for two nights. The first night served as an adaption night to the new environment. In total, 44 smokers were compared with 44 non-smokers. On average, smokers smoked 21 cigarettes a day and had smoked for 13 years. All participants were monitored with polysomnography and smokers were asked to provide a blood sample prior to sleep, in order to quantify levels of nicotine and cotinine (the metabolite of nicotine).
The main results were that smokers, relative to non-smokers, took (objectively) longer to fall asleep, spent more time in REM sleep, and had more evidence of sleep-breathing events and limb movements during the night (both known to disturb and fragment sleep). Also, higher levels of pre-sleep cotinine and nicotine were associated with less deep sleep. Self-reported sleep quality was also worse in this group relative to non-smokers.
The authors conclude:
“In summary, sleep disturbances, which can affect daytime wellbeing and mood, are frequent among smokers. We detected reduced rating of sleep quality as well as changes in sleep architecture in a population of healthy young smokers, carefully controlled on other sleep-influencing variables.” The study team also suggest that future work should consider how sleep disturbance may be a risk factor for smoking relapse, in those attempting nicotine withdrawal, since sleep is know to be adversely impacted during this period.
Jaehne, A., Unbehaun, T., Feige, B., Lutz, U.C., Batra, A., Riemann, D. (2012). How smoking affects sleep: a polysomnographical analysis. Sleep medicine 13(10), 1286-1292.