My OCD upstairs neighbour and his late-night balcony door frenzies

My upstairs neighbour is driving me batshit. I have no idea what his problem is, but he seems to have some sort of out-of-control OCD compulsion to slide his balcony door open and closed over and over and over again, late at night/ early in the morning, producing a deep and resonant rumbling which echoes in my apartment. This sound has sometimes kept me awake nights, but tonight was a first - he managed to do it so frequently at 4am that it woke me up out of a sound deep sleep (I'd gone to bed at 12:30am and was NOT ready to wake up, thanks). I'm guessing he did it some forty times - twenty open, twenty shut - between 4am and 4:10; it's hard to say, since I didn't start counting until his initial intense burst of sliding was over, but between 4:10 - when I turned on the light and peered out of my sleep mask to see what fucking time it was - and 4:33 he opened and closed the patio door six motherfucking times, which has nothing on the frequency of opening and closing that preceded it. The sheer mystery as to what could be behind this behaviour is part of what makes it impossible to ignore, since after the twentieth instance you can't but help wonder what the holy hell he's up to. Is this an early-morning burst of chainsmoking? A drug induced tic? Is he checking to make sure the moon is still in the sky? Gaah! (He just did it again, at 4:40; rumble open, rumble shut; then again at 4:42, as I sit here). I was deeply, soundly asleep, and I do not fall back to sleep easily once I am awakened. Time to write him a terse but polite note: could he find another hobby, please?