Smoking and incidence of insomnia: a systematic review and meta-analysis of cohort studies.
OBJECTIVE
This study investigated the impact of smoking on the incidence of insomnia.


STUDY DESIGN
Systematic review and meta-analysis of cohort studies.


METHODS
PubMed, EMBASE, Web of Science, Cochrane Library, and OVID were searched through March 2020. Cohort studies reporting the effect of smoking on the incidence of insomnia were included. We quantitatively analyzed the basic framework and study characteristics and then pooled estimate effects with 95% confidence intervals (CIs) of outcomes of each included study using fixed-effects meta-analyses.


RESULTS
This systematic review included six cohort studies involving 12,445 participants. Quantitatively summarized results suggested that smoking could significantly increase the incidence of insomnia (odds ratio [OR]: 1.07, 95% CI: 1.02, 1.13). Regular smoking was significantly associated with the incidence of insomnia (OR = 1.07, 95% CI: 1.01, 1.13). As for occasional smokers and ex-smokers, the pooled analysis did not indicate a significant association (occasional smoker: OR = 2.09, 95% CI: 0.44, 9.95; ex-smoker; OR = 1.02, 95% CI: 0.67, 1.54). Subgroup analysis by age, gender ratio, and region showed a statistically significant relationship between smoking and the incidence of insomnia in specific groups.


CONCLUSIONS
Integrated longitudinal observational evidence identified smoking as a significant risk factor of insomnia. Considering the limited amount of available studies, more high-quality and prospective cohort studies of large sample sizes are needed to explore details of this association.
['Hu|N|N|', 'Wang|C|C|', 'Liao|Y|Y|', 'Dai|Q|Q|', 'Cao|S|S|']
D015331:Cohort Studies D006801:Humans D015994:Incidence D011446:Prospective Studies D007319:Sleep Initiation and Maintenance Disorders D012907:Smoking
Smoking Insomnia Meta-analysis