I asked my medical doctor if I could have a sleep study done, because I got to the point where I couldn't drive safely for more than a 45-minute trip. I would also be half asleep quite often when conversing with someone, even though my eyes would try to stay open. I didn't have sleep apnea, so the next step was a daytime study, which showed I had narcolepsy. I take methylphenidate (generic Ritalin) and it helps me to have a somewhat "normal" life. It's been used for narcolepsy treatment since the mid-1930's, and I don't have any ill effects from it. I would encourage you to see your doctor, because there are many physical issues that could cause this. Hope you get some answers.