The Interplay Between Addiction to Tobacco Smoking and Sleep Quality Among Healthy Adults

Scientific background Tobacco smoking is a major health problem, leading to considerable morbidity and mortality due to cancer, pulmonary illnesses, and cardiovascular diseases (Taghizadeh, Vonk & Boezen, 2016). The main psychoactive and addictive substance in tobacco is nicotine (Zaparoli & Galduroz, 2012). Nicotine addiction is a complex phenomenon that involves both physical and psychological dependence (Cohrs et al., 2014), which causes not only difficulty in quitting but also a strong tendency to return to smoking after having quit for a long time) Zaniewska, Przegalinski & Fillip, 2009).

A common theoretical model of addiction (Koob & Volkow, 2016) holds that the transition from occasional smoking to addiction involves an upregulation of neurobiological stress systems. Consequently, even a brief period of abstinence from smoking, leading to reduced concentration of nicotine in the body, induces both emotional withdrawal symptoms (anxiety, restlessness, irritability, anhedonia) and cognitive withdrawal symptoms (diminished memory and attention) that may in turn produce a compulsive urge to smoke again, in order to ease the unpleasant sensations (Koob & Volkow, 2016). Although some studies suggest reduced quality of sleep is also among the consequences of smoking and smoking cessation (Cohrs et al., 2014; Colrain, Trinder & Swan, 2004) this issue was not fully explored, and the contribution of the reduced quality of sleep to negative emotional situations and to the motivation to smoke is unclear.

Smoking and sleep. Smokers report more sleep disturbances such as insomnia (i.e., a variety of complaints reflecting dissatisfaction with the ability to initiate and maintain sleep, along with a significant reduction in total sleep time followed by daytime sleepiness) (Kaneita et al., 2005; Phillips & Danner, 1995), and a correlation was found between the level of addiction to cigarettes and reduced quality of sleep (Palmer, Harrison & Hiorns, 1980; Patten et al., 2000). A deleterious effect of smoking on the quality of sleep could partially result from disturbed pulmonary function (Simon-Tuval et al., 2011). Indeed, heavy smokers are at high risk for Chronic Obstructive Pulmonary Disease (COPD) (Tarasiuk et al., 2006), which causes disturbed sleep leading to reduced quality of life (Scharf et al., 2011; Won & Kryger, 2014). Moreover, even in young, seemingly healthy, moderate smokers there is a clear reduction in pulmonary function, and a negative correlation was found in healthy adults between pulmonary functioning and sleep quality (Phillips et al., 1989). However, this factor could not solely explain the relationship between smoking and quality of sleep, as studies have shown an increased number of awakenings in the course of the night during early phases of smoking cessation (Hatsukami, Hughes & Pickens, 1985; Hatsukami et al., 1988).

The reliability of subjective sleep measures is not unequivocal and needs support from objective measurements (Pillar, Malhotra & Lavie, 2000). To date, only a handful of studies compared the sleep architecture of active and quitting smokers to that of nonsmokers using polysomnographic (PSG) tests (consisting of brain wave, muscle tension, eye movement, and other measurements). These studies confirmed the deleterious effects of smoking and smoking cessation on the quality of sleep. Zhang and colleagues (2006) found that compared to nonsmokers, the sleep of smokers was characterized by shorter duration, longer time to reach (rapid eye movement) REM sleep, longer time spent in light sleep (stage 1), less time spent in deep sleep (stages 3 and 4, slow-wave sleep-SWS), and lower sleep efficiency (percentage of actual sleep time of the total time spent in bed). Similarly, sleep duration among smokers was shorter than among nonsmokers (Jaehne et al., 2012). Likewise, PSG tests conducted on individuals undertaking smoking cessation demonstrated increases in the number of awakenings at night (Prosise et al., 1994), shortening of REM latency, shortening of SWS sleep duration, and extension of the phases of light sleep (stages 1 and 2) (Moreno-Coutiño, Calderón-Ezquerro & Drucker-Colín, 2007; Wetter et al., 2000), all indications of reduced quality of sleep. Yet, these PSG studies also had limitations as they were usually conducted on a small number of patients on a single night, under the artificial conditions of sleep laboratories.

Quality of sleep, stress, and addiction to smoking. It is well accepted that sleep plays a vital role in health as well as behavioral and emotional stability (Scharf et al., 2010; Tarasiuk et al., 2005). Those who suffer from poor sleep quality exhibit higher rates of psychological stress, depression, and various anxiety symptoms than the general population (Fernández-Mendoza et al., 2009; Ohayon, 2005). The tendency toward poor sleep quality among smokers and quitters, and the correlation between proper sleep and behavioral and emotional stability raise the hypothesis that the impairment in sleep quality among smokers and quitters affects their psychological functioning and their smoking behavior. The few studies that investigated this issue demonstrated that abstaining from cigarette smoking for 48 hours increased the subsequent rate of smoking (Hamidovic& de Wit, 2009), and that sleep disruptions during withdrawal have a negative effect on the success of smoking cessation (Jaehne et al., 2009; Persico, 1992). These findings seem to integrate well into the aforementioned theoretical model, which holds that exposure to nicotine leads to the development of aversive psychological symptoms when the bodily nicotine concentration drops, which leads to a compulsive urge to smoke to alleviate these unpleasant sensations (Cohen & George, 2013).