My Friend Has A Concussion And She Was Given A

My friend has a concussion and she was given a pill that started with amb. Trine?.something or something like that is mostly used as an antidepressant but they are giving it to her to help her sleep but
it gives her very bad nightmares
Do you know what this drug could be or if there are others in the family of drugs that might help her without the nightmare side effect?