This induces lethargy after around ~10 breaths (the upward limit). These are around 3 second hits we'll say. It does provide a nice feeling of having worked or feeling tired, not to the point where you get euphoria from laying down but enough to want to lay down. As is the nature with melatonin it will leave your brain still decently active, so don't expect to get knocked out. Overall I recommend for people who struggle with tossing and turning or lighter ADD or similar.