I am a 51 yr. old, 135 lb. female. I have experienced some tightening in my chest when laying in bed, either first thing in the morning or in the evening when I am ready to sleep. It has happened 4 times in the last month. It lasts approx. 30 seconds to a minute. My husband thinks it is because I have been on the elliptical machine for 45 minutes and it is muscle strain. He may be right, but I am a little concerned due to the fact my 46 yrs. old brother had a heart attack and he was in good health. I am in very good health and exercise regularly. At my last physical I did have an EKG (in November) and it was fine. should I be concerned??