In assessing a 31-year-old man with chronic back pain, which symptom is part of the diagnostic criteria for potential substance use disorder?

Craving medication is a key symptom in diagnosing potential substance use disorder. This indicates a strong desire or urge to use a substance despite the awareness of its potential harm or the negative consequences associated with its use. Cravings reflect an individual's psychological dependence on the substance, signaling that the person may prioritize obtaining and using the medication over other important aspects of their life, which is a critical aspect of substance use disorders.

Other options, while they may appear related to behavioral changes, do not fulfill the diagnostic criteria for substance use disorder. Devoting more time to social activities does not inherently indicate misuse, and experiencing good sleep typically suggests a stable mental state rather than a disorder related to substance intake. Unusual aggression may indicate a range of issues but does not specifically correlate with craving or dependency, which are more tightly linked to substance use disorders. Hence, craving medication stands out as a clear indicator of concern in this context.