I take 70 mg of Vyvanse in the morning and it typically lasts about 10 hours. That's usually enough to get me through my work day. I experience a resurgence of my ADHD symptoms in the evening when the medicine wears off. So far I haven't talked with my prescribing provider about an additional dose of medication (something short acting) in the evening for fear of being seen as a drug seeker. I may down the road if it continues to be problematic. For now though I'm happy to have the Vyvanse during the day. It's been life changing. And, coincidentally, I can nap a lot easier on Vyvanse than when I wasn't on it.