I am a 22 year old active female who has been healthy for her entire life. About four years ago when I started college - at night time when I would lie down to go to sleep I would get a heavy feeling on my chest and sometimes feel that I could not inhale enough oxygen. (like my throat was narrower than normal) It started occuring more frequently to somtimes when I was driving or at the movies - wherever. Fast forward to today - I have graduated college and do not feel that my life is stressful, but at night when I lie down (or ANY time I lie down) my chest gets "heavy" and i feel like it is "hard" to breathe. I have started getting heart flutters, once daily, at the most. I work out 4 or more times per week with no apparent problems. My doctor said that it was probably stress/anxiety and suggested that I try Zoloft. However, I'm not experiencing any major stress in my life and wonder if maybe I have developed a heart problem. Has anyone dealt with these symptoms and may be able to offer any advice? Like I said, it happens EVERY time I lie down. I dread going to bed at night because of this. Thanks so much for any help, this terrifies me.