Dextroamphetamine Sulfate is one of the strongest stimulants. The maximum dosage is considered 45 mg. daily. I like instant release as you can control when you take your med. Addictive, yeah. When I take a day or two off, I crash. I feel intense fatigue and I am completely unmotivated. I have managed to keep Dextroamphetamine just under the max with mild tolerance issues. I have also used Ritalin for 20 years. I switched to Dex. to give me a break. For me, my only side effect is poor appetite. This can be a problem. I am 5’5” and weigh 100. My last dose is around 12:00-1:00 PM. I can go to bed at 6:30 without having any sleeping issues. My blood pressure, heart rate, CO2 are in normal limits. Obviously, my weight impacts my numbers. Does it affect fatigue? Most definitely. I get about 2 1/2-3 hours out of a dose. I try to conserve energy after I take a 15 mg. dose. For me, stimulants can trick you into thinking you don’t need rest. You still need to refrain from overdoing it. Otherwise, you will feel fatigue and need more for the same effect. Don’t go that route. If you stay true to your prescription, you should be OK.