For the 1st 2 weeks, i had minor headaches. I was expecting it. On the 2nd week onwards, my mind is sharper, i feel like it has been upgraded 10X. I can multi task with greater speed and efficiency. I currently manage a high dependency unit (i am a nurse by profession) and run a staffing agency at the same time. Not to mention, i have a 2 yo daughter. I highly recommend it.