Stupor in psychiatric terms is a condition of reduced consciousness where it takes more than usual effort to bring about a reaction. For example, a person in a stupor may not notice when someone speaks to him unless the speaker shouts, and even then, the reaction may be sluggish. The person can make voluntary movements but these may lack coordination and lead to injury. There may be reduced response to pain.
Stupor is a possible side effect of many medications, including tricyclic antidepressants, Zyprexa (olanzapine), Xanax (alprazolam) and others.