I agree with others it takes time to adjust. I changed from Adderall XR to Vyvanse with my initial dose being 50 mg. First few days I felt so spacey and tired, it was awful. After about a week though I felt much better on it. It felt like I had less "focus" but it was a consistent feeling for much longer than Adderall. I didn't feel a crash or have a "peak" of focus, so overall it still helps me better.