obstructive sleep apnea/hypopnea syndrome
"I have been taking Provigil for several years now. I just started Nuvigil today, and it feels much different. It used to be that I took one Provigil and I would be sleepy and have fog head, but two Provigils made me feel wired and nauseous. Today I took one Nuvigil around 10:30 am and have felt even and awake all day long. Hopefully this will last."