Hello, I am a 29yo white male. Ht 6 ft, Wt 205. I am currently a senior nursing student. I have been taking Vyvanse 50mg for 7-8 months to treat symptoms of ADD, specifically inattentiveness. The medication works wonderfully as I have never been able to focus as well as I do now while on medication. However, in the past couple of months I have noticed myself getting frequently lightheaded, especially when moving from a sitting to standing position too quickly. I drink plenty of fluids throughout the day and stay pretty well hydrated. Also, I am very active with running and playing soccer, and I have noticed myself feeling out of breath more often than in the past, usually after a short sprint, and often accompanied with the same lightheaded feeling I get when I stand too quickly. My heart rate is good, usually about 60-70 at rest. And my BP is usually in the 110/70 range. Any ideas on what might be causing the shortness of breath and lightheaded?