Lately, I have been falling asleep for no known reason. I will be sitting watching tv and nod off. Do you know what could cause this?

I have fatigue that is interfering with my life--it’s all I can do to drive home after work and immediately crawl in bed. I have no new medications, and every test comes back normal. Are there any more specific tests I can have done to see if something is off?

Do afternoon naps help or disturb sleep later on at night?