Now I know why I had a nervous feeling yesterday. Last night and this morning I have had a migraine headache. I have been getting migraines for the past twenty years. My migraines and allergy symptoms were getting worse as I got older. The best explanation I've been given for the nervous feeling preceding the headache is the release of histamines by the body. Not sure if this is accurate.
The only reason I mention this is because I believe people who suffer from migraines can benefit greatly from running regularly.
Since I began running regularly four years ago, My migraines don't come as frequently and are less severe when I do get them. I have even gone for a run when my eyes began flashing (some people call it an aura effect) and relieved the symptoms of the headache which typically follows.