Have WPW, Acid Build Up. Trying To Quit Smoking. Fatigue, Rapid Heartbeat. Normal?

I'm a 23 year-old male. I have Wolfe-Parkinson's-White (WPW) and a huge problem with acid build up. Because of these two conditions, my doctors have stuck me to a diet. While I am still a casual smoker, I am trying to quit. I usually only smoke when I am out on the weekends with friends. Overall, I am a healthy, active, young person. However, I've been noticing that I have extreme fatigue. However, most of the times that I am feeling tired I am also experiencing rapid heart beat. Is this normal? I've found it very difficult to sleep the past couple of months because of this. The rapid heart beat normally subsides around 2-3am. What can I do so that my body will allow me to sleep earlier? I feel like this is key in curing my fatigue.