Sleep disorders characterized by insufficient sleep duration, irregular circadian rhythms, poor sleep quality, and insomnia are highly comorbid with substance use disorder (SUD). Many of the neurobiological substrates that have been associated with sleep deficiency and circadian rhythm disturbance are also implicated in drug use/addiction, reward/reinforcement, mood regulation, autonomic regulation/integration and pain perception (e.g. dopamine, hypocretin, norepinephrine, GABA, glutamate, adenosine), providing mechanisms through which the processes of sleep and substance use disorder can be interdependent. Drugs of abuse interact with neural substrates of sleep and arousal. Conversely, sleep or circadian dysfunction can increase vulnerability to SUD and influence SUD treatment response and recovery outcomes. For example, sleep disturbance is one of the primary complaints of those recovering from opioid use disorder implicating modification of sleep as a potential treatment in tandem with current pharmacological and behavioral therapies. This meeting brings together experts in the fields of sleep, circadian rhythm and SUD to highlight neurobiological mechanisms underlying the comorbidity of sleep/circadian dysfunction and SUD, identify gaps in knowledge and propose future directions that advance the treatment of sleep disorders, SUD and their comorbidity.