I had a lot of test done to find why my heart beats crazy fast all of the sudden...sometimes I am laying in bed quite, sometimes I am pretty stressed, and sometimes when I hiccup..... it races for sometimes 5 or ten minutes...never more than that....sometimes laying down or inverting stops it. always get a head rush when it stops, I am a little shakey ....then after for couple minutes then I feel fine. doctor told me my heart is great....it may have been the sudaphed and zantact I took with in a couple minutes of each other.....I have had this for many years.....I drink one cup of coffee every morning(1 a day only) 30 years ago used to drink 10 a day. I am 56....5-10 1/2 tall...180lbs.....work out regularly. Also seemed that a few years back I would have these a lot....found out that crystal light caused it.....with further investigation it was aspartame? I think(sweetner) in it...is that possible? I only have I an attack every once in a while ....instead of almost everyday when drinking crystal light. any thoughts? Thank you.