hey there
Ive also been fighting daytime sleepiness for a long time. Polysomnography didnt come up with anything, same for bloodwork etc.
I've tried many stimulans (methylphenidate, Lisdexamphetamin-Dimesylat etc.)
What works for me now is taking modafinil. That isn't really a fix tho. Merely a "bandaid"...
I dont feel more daytime sleepiness than "healthy" people anymore (on most days). But there still are days, on which I can fall asleep anywhere, despite taking medication.
Have you tried any medication against sleepiness/tiredness?