Why can’t I stay awake?

Hi,

I’ve been struggling with staying awake for a couple of years now. I sleep really well, about 8 to 9 hours per night, with a regular schedule. However, when I listen to a lecture, attend a meeting, a presentation or something that doesn’t stimulate me, there’s a high chance I’ll start nodding.
I do not feel tired during the day, and when I fall asleep I can’t fight it nor control it. When Im alseep I seldom continue taking « notes », but its all just scribbles. Often I will not realise I fell alseep when I wake up. Two or three times I even saw things while waking up, hallucinations in my vision. For example, a line of text became a line of bright green numbers, moving rapidely up and down, when there was just a normal, unmoving sentence in reality.

It doesn’t happen everyday (when I cant help but fall asleep during the day), maybe three to five times a week. Sorry for the long paragraph, I am just worried. Do you know what could be the cause of this?

Thank you,

Marie-Ève D.