Your are having a sleep deficit. You have not been sleeping well may be for weeks, months or years.
What you need to do is to continue sleeping as much as your body want you to sleep. May be continue sleeping at 11 hours daily. Find time to sleep more on weekends or during lunch breaks. Avoid all stimulants including caffeine. Do this for several weeks or months. There will come a time where you will not be sleepy or tired anymore. When you get here your mind and body will be operating at your best.
Then your concentration will improve, you may also stop gaining weight. Your cognitive skill, intelligence, reaction time and creativity will actually improve. Your heart and other bodily functions will also improve.
Then sleep as you need, though you may not need as much as 11 hours daily.
Stop going back to taking stimulants, and other things that will distract you from normal sleeping habits.
I have experienced this many times in the past and these measures always works. My recommendations are also supported by recent findings by the scientific community.