WatchOver: using Apple watches to assess and predict substance co-use in young adults

Simultaneous alcohol and marijuana (SAM) use can significantly impact young adults' physical and mental well-being. While SAM use is becoming increasingly prevalent in this population, there has not been much work to monitor and understand related behaviors and contexts. We aim to address this gap by using smartwatches to collect ecological momentary assessments (EMAs) and sensor data. In this paper, we describe the design and development of the smartwatch framework focusing on SAM use. We also collected pilot data from an n=1 deployment over 7 days using the framework. Our findings indicate that EMAs on smartwatches can be completed with lower perceived burden, which is important for longitudinal SAM use data collection. We also provide design guidelines and rationale for future work aiming to use smartwatches.