ABSTRACT Background Alcohol-related harms are prevalent late at night, especially on weekends, when high levels of intoxication contribute to increased rates of injury and violence. Reducing or increasing alcohol trading hours late at night in bars and clubs is generally associated with reduced and increased harms, respectively. This study evaluates the impact of later alcohol trading hours in the Scottish cities of Aberdeen and Glasgow on alcohol-related ambulance call-outs and crimes. Under local policy changes, 38 bars in Aberdeen had trading hours extended between 1 to 3 hours up to 3am, and 10 nightclubs in Glasgow had a 1-hour extension to 4am. Methods Following a natural experiment evaluation framework, we used a controlled interrupted time series design to compare outcomes before and after policy changes, from 2015 to 2021. The primary outcome was a count of total weekend night-time alcohol-related ambulance call-outs. Secondary outcomes included weekend night-time crimes. Results In Aberdeen, the policy led to a significant relative increase of 17·4% (effect size=7·061; 95% CI=3·902 to 10·220; pConclusion Later alcohol trading hours had a significant negative impact on alcohol-related ambulance call-outs in Aberdeen (where more premises had longer extensions) but not in Glasgow, suggesting the number, capacity and type of premises moderated outcomes. This is important for the design of future national and local licensing policies and regulations. KEY MESSAGES What is already known on this topic? Prior research has shown a strong association between alcohol availability, including late-night trading hours, and alcohol-related harms. Systematic reviews report that reducing hours of alcohol sales is linked to decreased alcohol-related ambulance-callouts, assaults, and road accidents, whereas later trading hours tend to intensify these alcohol-related harms. International studies, such as those conducted in Netherlands, Norway, and Australia, have provided empirical evidence that even modest reductions or extensions in trading hours can lead to significant decreases or increases in alcohol-related ambulance call-outs, crimes, and emergency department visits. What this study adds? This study provides novel and robust evidence on the impact of later trading hours for bars and clubs on alcohol-related ambulance call-outs and reported crimes in Scotland, using a controlled interrupted time series (CITS) design. By focusing on local policy changes in both Aberdeen and Glasgow, where certain venues of different types were permitted to extend their alcohol trading hours, this research leverages a natural experiment to provide novel insights. Our evaluation provides new evidence on the importance of local contexts on the magnitude and timing of change in trading hours for informing future policymaking decisions and research. How this study might affect research, practice or policy? Our findings raise important questions for policymakers seeking to balance economic and community interests in late-night entertainment with the negative impacts of such premises on services including: what is a proportionate policy given our evidence? Is it legally possible for current licensing systems to contain later trading hours to a subset of premises? And, if so, how would those premises be selected?
Sheikh et al. (2026) studied this question.