Need a new tactic to stop teens from puffing on Parliaments between classes? Warn them of looming insomnia. Cigarette smokers who get hooked as teens get less, worse sleep in their 30s. Or that was the case in a twenty-year-long study from the NYU School of Medicine. The findings were recently published in the journal Substance Use and Misuse.
It's fairly well-established that smoking and sleeping don't go together, with cig-lovers combatting disturbed sleep throughout the course of their habit. The smoking-insomnia link shows up when researchers dig into public-health data. For instance, one 2012 study referred to by the NYU researchers showed that middle-aged women with histories of chronic smoking had significantly higher rates of insomnia. And the link shows up in both biology and sleep studies. It's thought that nicotine contributes to insomnia by indirectly affecting brain chemicals involved in arousal, as well as by potentially inhibiting the function of sleep-promoting neurons. Compared to non-smokers, EEG recordings showed that dozing smokers exhibit more frequent brain waves associated with wakefulness. Also, analysis of sleep architecture (i.e., how a night of sleep is built, in terms of sleep stages) revealed that cig-lovers take longer to fall asleep, get shorter nights of rest and spend more time in light sleep.
While plenty of research depicts this relationship as causal, rather than merely correlative (i.e., smoking breeds sleeplessness), we don't know much about how longterm smoking rubs off on sleep patterns over time. But the current study assessed exactly that: Beginning in 1990, researchers spent 20 years tracking the health and lifestyle habits of 674 black and Puerto Rican teenagers from New York City. All in all, participants filled out six questionnaires on their cigarette use and insomnia symptoms, including difficulty falling or staying asleep, waking up too early and daytime sleepiness. By the end, participants were in their early-to-mid 30s.
Researchers predicted a higher incidence of insomnia among participants who'd smoked steadily and heavily enough since high school to qualify as "moderate" or "chronic" smokers. They controlled for other demographic and lifestyle factors likely to affect sleep, including gender, educational status and BMI. Their prediction bore out, and their findings closely matched those of previous studies — teen smokers who didn't ditch their habit grew into troubled sleepers. For daytime chain-smokers, insomnia symptoms likely stemmed both from nicotine itself and nighttime withdrawl from it, researchers posited. Twenty percent of heavy smokers reported waking up during the night in need of a fix.
But, beyond affirming the general smoking-insomnia link, researchers sought to make sense of the pronounced insomnia symptoms among smokers whose habits formed in the school yard. It's possible, they wrote, that cigarette use impaired the normal devlopment of brain systems involved in reward-processing and sleep patterns, which both undergo changes during adolescence.
This particular study involved teens who lived in the same city and identified as either black or Puerto Rican, so researchers can't be sure the findings apply to other groups. Regardless, the study does support integrating insomnia treatment into smoking-cessation programs. That way, ex-smokers might be better equipped to give up smoking and reclaim their Zzzs.