I HAD THIS SAME EXACT PROBLEM WHEN I WAS IN REHAB FOR 3-4 MONTHS. RIGHT BEFORE I WOULD FALL ASLEEP, i would lose my breath and would have to immediately sit up and catch my breath, i would get dizzy too, and my chest would feel like there was pressure on it. i only get this weird phenomenon as im laying down right before i start to drift off, sometimes i would get super dizzy like im on a roller coaster, and would have to get out of bed, sometimes my chest and heart would pound. I WAS CONVINCED it was a heart issue, as my grandfather died of a heart attack at age 30, and my uncle just had a heart attack, his 2nd one and is in his 50's..so i got all types of tests done, and everything came back normal. the asshole shrink kept telling me it was panic attacks, and that not even the medicine i was on (Trazadone) will cause what i was going through, i cussed his ass out, i thought i knew what a panic attack was, but wow it really is a physical issue and feels so real and horrible....come to find out, the trazadone was the reason why i was having these episodes at night, i believe the term is called "vertigo", i stopped the trazadone, and symptoms went away...but its odd, i been on trazadone for years and never had the issue, actually when i started back on Trazdone and remeron at the same time thats when it happened, even sitting down, if i would doze off i would get very painful body sensations..and its a shame cuz remeron really helped with my depression, i dont care what that doctor said, ANYTHING IS POSSIBLE, even if that means a medication can cause the issues i had...it was a combo of panic attacks, and a reaction to trazadone