Inhalant use is associated with sleep quality and mental health during the COVID-19 pandemic

RATIONALE: Cigarette smoking and sleep quality are known to impact mental health considerably. As nicotine is a primary component of both cigarettes and electronic (e)-cigarettes, we launched a survey-based study in order to study the effects of e-cigarettes, conventional tobacco, and dual usage on mental health as well as sleep quality. We sent out this survey in the time of COVID-19 in order to assess the impact of nicotine-based inhalant use on sleep quality and mental health. We hypothesized that e-cigarette use impacts mental illnesses and sleep quality, which is exacerbated by the presence of additional stress such as a global pandemic. METHODS: We combined our established UCSD Inhalant Questionnaire with the Pittsburgh Sleep Quality Index (PSQI), Hospital Anxiety and Depression Scale (HADS), and Patient Health Questionnaire (PHQ-9). Participants were recruited through online advertisements posted to social media sites including Facebook, Craigslist, Reddit, and Twitter. Participants (n=554) were recruited in April 2020, and a subset (n=217) retook the survey in June 2020. The survey was broken up into four sections - past and current type of inhalant use (UCSD Inhalant Questionnaire), PSQI, HADS, and PHQ-9. All participants were incentivized via a weekly lottery for a gift card. RESULTS: Inhalant users reported worse sleep quality (PSQI, 6.74) when compared to non-smokers/non-vapers (PSQI, 5.72, p=0.02). Higher anxiety scores were associated with worse sleep quality (linear regression, r2=0.28, p<0.001). E-cigarette users and dual users of both e-cigarettes and conventional tobacco had higher anxiety scores (HADS anxiety;12.08 and 11.37, respectively) than non-smokers/non-vapers (7.94, p=0.028). Dual users were found to have higher depression scores relative to controls as well (HADS depression;7.42 versus 4.68, p=0.017). Sleep quality improved during the COVID pandemic from April 2020 (PSQI, 7.92) to June 2020 (PSQI, 6.10, p<0.0001). Interestingly, anxiety scores increased over the same period of time (HADS anxiety, 7.51 to 8.76, p<0.01). CONCLUSION: Our finding of diminished sleep quality in inhalant users is novel. Based on these data, we speculate that inhalant users may be more susceptible to sleep disturbances in the setting of a stressor, such as a global pandemic. Higher anxiety scores in e-cigarette and dual users, and higher depression scores in dual users, imply a direct relationship between inhalant use and mental disorders. Higher anxiety scores as the pandemic progressed may in theory reflect the lack of having an end in sight, or having loved ones affected by COVID-19.