My son has been diagnosed with adhd on Dec 10th so very recently. He has been on Vyvanse since Saturday morning. It started with 10mg and that meant me breaking open the capsule to give him half of the 20mg (lowest dose). The first day was great he was able to play with other kids and such but then the second day he was irritable and almost spaced out most of the day plus slept 4 hours plus it was wearing off early in the day around 2pm after giving at 7am. The doctor said to try the full 20mg since we are seeing different results....thought maybe I wasn't giving the full 10mg on one day and more then 10 on the next. To get an even idea of the med we went up to 20 every day. The was Tuesday and things have been fine. Then last night as I posted already he wouldn't go to bed. Tuesday night he did get mad when he was coming off the meds and threw books at me though.