I have taken modafinil on and off for several years because of a sleep disorder of not being able to fully wake up and chronic fatigue. I have sleep apnea. I stopped it for about 8 to 10:weeks and then started again on June 18 because I was tired of being tired. From the 20th to the 25thni felt dizzy, slight nausea, and just not well. On the 24th I went to a safari park and had some episodes of feeling dizzy and then could barely make it back walking to my car. Had trouble breathing, had to stop at every bench on the way out to catch my breath and recover. I am 81 swim laps and go to Pilates twice a week. I thought it was my heart. Texted cardiologist and they said they will watch. I have an implanted heart tracker. Could it be so simple that modafinil is causing it because I did not take it and started it again?