Question: how long does it take for unisom to leave your system?
Answer: Because of its relatively long elimination half-life (10–12 hours), doxylamine is associated with daytime/next-day drowsiness, grogginess, dry mouth, and tiredness when used as a hypnotic. The shorter elimination half-life of diphenhydramine (4–8 hours) may give it an advantage over doxylamine in this regard.