Somnolence is one of the most common adverse effects of a dopaminergic agonist, rotigotine. We report putative adverse effects experienced by a spouse of a man treated with this compound because of advanced Parkinson disease. We propose the exposure to rotigotine through the seminal fluid because protected sexual intercourse eliminated her postcoital symptoms. This previously unrecognized mechanism may be more common and associated with other psychoactive compounds penetrating the blood-testis barrier, and it may account for otherwise unexplained postcoital somnolence or fatigue.