Its that period of time just after you get into bed, when your body begins to relax.
Your eyes are half open and the rods in your retina reproduce a dim grainy image of the hallway and bathroom door, lambently lit by an outside light - filtered and softened by the frosted bathroom window.
And in apparent inverse reciprocation to the winding down of your body, your mind begins an increasingly intensive review of the day that has just been. Problems in software are addressed and solved in a million different ways... strategies and solutions which were previously murky, wavy and unclear suddenly snap into brilliant sharp focus, and as the mind-spidering just goes on and on, the events of the last 24 hours all interconnect, each providing insight and forward motion to the other. And it builds and spins faster, until it goes beyond useful thought - the images become surreal - and still your mind just keeps winding up, faster and faster until in just a single clock cycle it hits you - Bamm! ....you're asleep.
And you awake the next morning knowing that last night, after you tucked yourself in, you solved all the problems of the world.
And you're totally gutted, knowing that the system shut down before you could save your work. You search for the .tmp files, but the folder is empty.