This is my 5th day on 150mg of Nuvigil. I really havent experienced wakefulness yet. Im still very tired, all day. I tried to not take caffeine but since i have to work i have to have some sort of caffeine to stay awake. The first 2 days of taking it i didnt have caffeine, and i took it on an empty stomach. waited an hour to eat. Ive taken it at different times to see if that would help, pretty early id say. 9am or 10am, and by around 5-7 im a little more awake but not enough to lay down and NOT sleep. I would still be very tired. I suffer from constipation so i dont know if that could be the problem or it will just take longer for me to notice anything? And if so how long? Im still wondering if i should ask my doctor to up it to 250mg