Both withdrawal symptoms and external stressors can contribute to relapse in people that are trying to quit using marijuana. These negative feelings may be more severe in people that also have Major Depressive Disorder, making it especially hard for them to quit. The purpose of this study is to examine differences in withdrawal symptoms and stress response in people with Cannabis Use Disorder that do or do not also have major depression. Study participation will involve 3 on-site laboratory visits over 6 days. Participants will be asked to not use marijuana for 3 of those days. Participants will complete mobile phone surveys multiple times each day, wear a watch to assess sleep quality, and provide blood samples for testing at each laboratory visit. At the final laboratory visit, participants will complete a stress task.

The purpose of this study is to determine if certain chemicals in the body, called endocannabinoids, are affected by heavy marijuana use or marijuana withdrawal. Participation lasts approximately five weeks. In the first week, participants can use marijuana as usual and will complete mobile assessments asking about their current feelings four times each day for seven days. Participants will also complete three 5-hour laboratory visits during this week to assess levels of endocannabinoids in the blood at different times of day. One month after the first laboratory visit, participants will complete the same tasks (three laboratory visits and daily mobile assessments) while maintaining abstinence from marijuana for one week.