I dont take valium for sleep (well not officially although sometimes i do) I have it for when my anxiety gets very bad. BUT it makes you very drowsy (well depending on the dose, and your tolerance, but it will make you drowsy) they do work, they have different effects, they can make me feel really stoned and out of it but my friend gets quite giddy but still sleeps, i have noticed you feel abit rough in the morning, but no where near like a hangover.