i think something that also plays into this is that coping in everyday life with adhd is mentally exhausting mental exhaustion unlike physical exhaustion isnt always obvious and can be brought on by a lot of different factors including sensory overload stress overwhelming emotions normal everyday living and so on its like telling someone to run a 100m sprint after running a marathon you could technically do it but not right now  on top of that mental exhaustion doesnt always translate into being able to sleep when your physically exhausted but your mind is still overly active falling asleep is also hard so sleeping while your bodys energy level is still high would also be hard  also this is reason 713 why adhd is exhausting