Also couldn't sleep. The first 4 hours were ok, since I had lots of good ideas about something I'm working on, but then the part of my brain responsible for executive functions partially shut down from exhaustion and I lost most of my planning and problem solving abilities, so the next 4 hours were less interesting and less productive. I managed to slip into something resembling a light sleep for about an hour before getting up this morning.
Does anyone else get physical sensations in their head depending on what their brain is up to? I can feel various combinations of warmth, pressure, lactic-acid burning, blood vessels dilating or constricting and my pulse beating in my head when I'm having a productive brain-storm, with the sensations localised across my forehead and the front half of the top of my head and a little bit down the sides between my ears and temples. There's a cool, tingling, heavy sensation in the same areas when my brain gets tired of grinding away at problems and starts to selectively shut down.
When I have a bad day, I often have a tight, numb sensation in my forehead, and it becomes more noticeable when I try to do things that require a lot of executive control. On worse days, when my ability to think clearly and deal with life's challenges has completely gone to shit, it feels like there's a lead blanket draped across my forehead and the front half of the top of my head.