The expression NOD is used to describe someone under the influence of what drug?

The expression NOD is associated with someone under the influence of heroin. This term specifically refers to the state of drowsiness or sleepiness that individuals may experience when they are using opioids like heroin. This sedative effect is a characteristic feature of opioid use, where individuals may appear to be in a semi-conscious state, often nodding off during conversations or activities.

Heroin depresses the central nervous system, leading to relaxation and a sense of euphoria, but also significantly impacting alertness and responsiveness, contributing to the "nodding" behavior. This is in stark contrast to the effects of other drugs like meth, cocaine, or PCP, which generally produce more stimulating or hallucinogenic effects rather than a sedative or tranquilizing response.