i feel breathless when i'm almost asleep...

This condition generally occur to one who is very sensitive in nature and one who is facing very stressfull situations in life example like nearest ones death, failure in life like...
my suggestion is to do take deep and relaxed breaths daily for five 30 minutes starting from five minutes increasing to 30 minutes in one month period.
remember that you dont hav to take anything intake while doing this. and your stomach should be empty. so do this after four hours after eating anything big or drinking anything more. do it in relaxed manner.
hope you will get good results