Closing window

I couldn't open my eyes after the midnight sleep. I got up and fall asleep again for another 40min. I was trying to do some housework to keep awake but collapsed on the nearest bed and fell asleep for another 40min. Woke up and forced myself again to keep going and was falling asleep while trying to read the e-mails. I only regained full consciousness at 3.30am! This is crazy as I have to catch another nap at 4am. Those naps between midnight and 4am are not my best thing at the moment. I don't know what's going on. I feel great for the rest of the day and night but this window for some reason is shutting down on me.