Chronotype, Social Jetlag, and Nicotine Use

Abstract

Late chronotype, which often leads to higher social jetlag (SJL), is strongly associated with the prevalence of smoking. Any circadian disruption, strain, or misalignment, results in people not being able to live according to their biological time as is described by SJL, which we will therefore use as umbrella term. We hypothesized two scenarios potentially explaining the association between smoking and SJL: (A) If smoking delays the clock, circadian phase should advance upon quitting. (B) If people smoke more to compensate the consequences of SJL, circadian phase should not change upon quitting. To distinguish between these two hypotheses, we accompanied participants of a smoking cessation program (not involving nicotine replacement products) across the cessation intervention (3 weeks prior and 6 weeks after) by monitoring their circadian behavior, sleep quality, and daytime sleepiness via questionnaires and actimetry. Our results show no effects of cessation on SJL, chronotype, sleep quality, or daytime sleepiness, thereby favoring scenario (B). Thus, smoking may be a consequence of rather than a cause for SJL. Daytime sleepiness was a significant predictor for the outcome in our model but did not improve with cessation.

Exploring the role of nicotine and smoking in sleep behaviours: A multivariable Mendelian Randomisation study

“…Effects of both NMR and CPD on sleep traits were typically more prominent in current smokers than former smokers, suggesting that the effects of nicotine and smoking intensity on sleep traits are not long-lasting. In contrast to our findings, a recent study found that smoking cessation without nicotine replacement therapy did not affect chronotype, sleep quality or daytime sleepiness (Ghotbi et al, 2023). However, in that study sleep was assessed only 6 weeks after smoking cessation, which would not capture the long-term effects of cessation and the study was likely underpowered (n=49).…”

“…Previous studies have reported a higher prevalence of smoking among those with an evening chronotype (Ghotbi et al, 2023;Patterson et al, 2016).…”

“…This is important as it suggests, among smokers and for a given level of smoke exposure, those with a slower nicotine metabolism (i.e., higher circulating nicotine) might stay awake longer in the evening (due to nicotine arousal effects) while those with a higher nicotine metabolism (i.e. lower circulating nicotine) might wake up earlier (e.g., due to craving) (Ghotbi et al, 2023). We also found that a higher NMR was associated with an increased likelihood of napping and daytime sleepiness among current smokers, again suggesting less arousal in those with lower circulating nicotine.…”