The present study aimed to assess changes in substance use and other reinforcing behaviours in a large sample of young men from before to during the first wave of the COVID-19 crisis in Switzerland and to investigate whether this affected substance use and other reinforcing behaviours differentially in certain subgroups. Results showed significant decreases of approximately 17% for drinking volume and HED frequency. These reported changes may reflect the immediate impact of COVID-19 measures on the availability of alcohol (Rehm et al., 2020). Since alcohol use is one of the main risk factor for mortality and morbidity (Rehm, Taylor, & Room, 2006) and HED is one of the strongest predictor of alcohol-related harm, e.g. blackouts, accidents, problem with the police, violence, among young adults (Gmel, Rehm, & Kuntsche, 2003; Wechsler, Davenport, Dowdall, Moeykens, & Castillo, 1994), a decrease in alcohol use is good news for public health. The open question is whether this decrease will be maintained over time. As opposed to alcohol use, significant increases of approximately 75% more time spent gaming and watching TV series were found. This result may reflect participants’ increased free time and the availability of special offers during the COVID-19 crisis, as well as the engagement in these activities as coping mechanisms in response to the increased stress and burden caused by the COVID-19 crisis. High involvement in such activities is not problematic by itself (at least for gaming; Király, Tóth, Urbán, Demetrovics, & Maraz, 2017). Gaming may even be beneficial to relieve stress, reduce loneliness and increase well-being in general (Johannes, Vuorre, & Przybylski, 2021; Johnson, Jones, Scholes, & Carras, 2013; Kaye, Kowert, & Quinn, 2017; Reinecke, 2009). This was also found in the context of the COVID-19 crisis (Barr & Copeland-Stewart, 2021). Thus, moderate increase in time spent gaming and watching TV series may be an adaptive response to the changes in daily routines and stress caused by the crisis. However, for a minority of users, high involvement may progress into long-lasting problematic patterns of use. Professionals and policymakers may play a role to limit involvement in these activities by providing recommendations. As proposed by Király et al. (2020), these may include making a schedule of daily activities to keep a daily routine, the maintenance of a healthy lifestyle (e.g. regular physical activity, regular sleep, healthy food) and of social activities with family members and social interactions, the use of relaxation techniques and digital wellbeing apps, the awareness and regulation of one’s screen time, and seeking help from professionals or help lines if needed.

Changes in substance use and other reinforcing behaviours did not happen uniformly throughout the sample population. Thus, particular attention should be paid to subgroups who did increase their use. Working less or experiencing a deterioration in one’s work situation was associated with greater increases in time spent gaming and watching TV series. Consistent with the results of Rolland et al. (2020), showing that unemployment was associated with increased screen use, this finding may reflect the lack of social activities available due to COVID-19 measures, combined with more time available and the extra stress of being unemployed or partly unemployed during a lockdown. Those reporting no deterioration in their work situation were also found to have decreased cigarette use, whereas those reporting a deterioration did not change their cigarette use significantly. This relative increase was consistent with the results of Compton, Gfroerer, Conway, and Finger (2014), who showed that unemployment was associated with cigarette use.

Healthcare workers in contact with potentially infected people reported increased cigarette use whereas others did not change significantly their use. During the SARS outbreak starting in 2002, about 20% of all individuals infected were healthcare workers (World Health Organization (WHO), 2003). Thus, healthcare workers may suffer from higher levels of anxiety and stress because of increased workloads and fears of infection and may increase their use of cigarettes as a coping mechanism. No significant increase in alcohol use was found in this subgroup. However, given the evidence of an increase in alcohol use disorders prevalence among healthcare workers three years after the SARS outbreak (Wu et al., 2008), studying the COVID-19 pandemic’s long-term impact on substance use will be important.

Fathers increased their time spent gaming by less than childless participants. During lockdown, fathers spent more time on childcare because nurseries and schools were closed, grandparents were recommended not to look after children, and children were at home. Childless participants almost certainly had more free time available for gaming. Furthermore, participants living alone watched more internet pornography, whereas viewing by others did not change significantly. Being forced to stay at home during lockdown, social interactions and activities were particularly limited for those living alone, and they were likely more prone to social isolation (Marmet et al., 2021). They may have watched more internet pornography to pass the time and to counter potential decreases in their real-life sexual activity.

Participants living in French-speaking regions increased their time spent gaming and watching TV series by more than those living in German-speaking regions did. They also decreased their cigarette use by less than participants living in German-speaking regions. German speakers also showed a bigger increase in internet pornography, which had already been found to be more prevalent in German-speaking than in French-speaking regions before the COVID-19 crisis (Studer, Marmet, Wicki, & Gmel, 2019). Thus, with the exception of internet pornography, differences between linguistic regions may reflect the fact that French-speaking regions were more seriously affected by the first wave of the COVID-19 crisis than were German-speaking regions.

This study is not without limitations. The sample included only young Swiss men and results are thus not directly generalizable to other age groups, women or other countries. Using self-reported questionnaires may introduce biases such as social desirability or recall bias. Also, because the C-SURF pre-COVID assessment was spread out over almost a year, participants had different time intervals between their pre-COVID and COVID assessments. Despite only about 50% of the participants invited to answer the COVID-study doing so, results from our sensitivity analysis, including all non-respondents, yielded the same patterns of change (although the significance of two coefficients differed from the main analyses). Also, although reported changes in substance use and other reinforcing behaviours could be attributed to the COVID-19 crisis, they could partly reflect seasonal changes or personal developmental changes. The present study’s strengths include its large, non-selective sample. More importantly, it did not rely on retrospective pre-COVID period reports, as measures of substance use and other reinforcing behaviours from C-SURF were available.

To conclude, the present study suggests that, during the first wave of the COVID-19 crisis (until June 2020), there was a decrease in alcohol use (but not in cigarette or illegal cannabis use) and more time was spent on other reinforcing behaviours such as gaming or watching TV series (but not internet pornography). Substance use and other reinforcing behaviours increased more in some sample subgroups that were found to experience higher levels of psychological distress during the COVID-19 crisis (Marmet et al., 2021): those reporting changes in their work situation (deterioration, fewer working hours, more time spent working from home), healthcare workers in contact with potentially infected people, the childless or those living alone. These specific changes corroborated the hypothesis that substance use and other reinforcing behaviours were not only more likely to occur if they were available but also that may have served as a coping strategy if individuals experienced heightened stress and isolation during the crisis. One open question is whether these changes will persist, increase or decrease over time. This will depend on further developments in the COVID-19 pandemic, the measures taken to combat it, the occurrence and magnitude of the expected economic downturn, and potential changes in the socio-cultural landscape affecting the usage contexts of different substance and other reinforcing behaviours. Although this initial decrease in alcohol use is good news for public health, caution is warranted because substance use may increase in the wake of the post-COVID economic recession expected to occur in many countries. Close monitoring of further developments in substance use is thus recommended. As regards growing digital activities, efforts to prevent their progression to chronic patterns of excessive use (including addictions) may be needed.