Use of illicit substances is prevalent in the nightlife setting, particularly so in the dance scene. Recently, we see an increase in stacking or binging of different substances. Combining different substances can increase acute and sub-acute health risks. Relatively little is known about the order and the amount in which substances are combined on one night. Most data we have is cross-sectional and asks participants to reflect on the last month. In the Nightlife meter study we have developed a smartphone app that will ask respondents while they are going out what drugs they are taking and for some also how much. By asking people while they are going out, we circumvent any recall bias people might have when asked about their substance use days or weeks later. The presentation will feature some preliminary findings of the study. We will give you some insights on the types of drugs respondents combined and how often they did so. The data was gathered in the summer of 2018 in both the UK and the Netherlands.