This happened to my late dad many years ago. [Check out the video below.] In my family they say it was the beginning of his heart problems - but I remember it as the start of his depression. He was a conscientious guy, not one to miss work, but this experience sent him right back to bed - instead of doing what he did every morning: hit the pavements visiting clients, trying to sell wall coverings.
[The photo, though, is of him during World War II.]