Sounds similar to panic attacks in your sleep. Do you have allot going on, financial worries, Relationship issues. I know when I am laying in bed all my problems of the world lay right on my chest. My father passed in his sleep, heart attack at 52yrs. old. My brother who had a Major heart attack but survived after 9 attempts to resuscitate him was 45yrs old when it happened. Lucky for him he awoke from sleeping and called 911 because of chest pains and then collapsed as soon as he opened the door for Paramedics.
I am 44 and I get a little nervous every night when I am falling asleep. It sucks having the family history that I do.

Good Luck OP, find another Doctor for 2nd and 3rd opinions. It is your life you are talking about.