I am 6 feet tall and weight about 200 pounds and was recently was prescribed 30 mg Adderall (not extended release). I take one half of one in the morning around 8 and the other half right around lunch time. I feel like every time I take this dose, it wears off around 4 or 5 in the afternoon. I have much studying to do this week and need as much focus as possible, so my question is, would it be harmful for me to take another half (15 mg) around 4 in the afternoon to get studying done long into the night?