ive been dealing with this really badly for the last few weeks in part due to sleep deprivation caused by other health issues  i read about a phenomena of involuntary sleep sometimes happening when people are overstimulated particularly people with adhd like your brain just hits a point and nopes out of consciousness   ive never been one to fall asleep during lessons but back when i was in school during 1 on 1 dutch tutoring i used to literally be unable to keep my eyes open and eventually slump down on the desk  so maybe the anxiety of confronting the task at hand combined with the stress of doing it is raising your stimulation to a point where you feel the need to sleep  edit nevermind its not high-stimulation its extreme boredom and the phenomenon i was describing is called intrusive sleep