Eyelid twitch

For the first symptom of prolonged sleep deprevation is an eyelid twitch. It can drive you crazy and for me it can take a few days of sleep before it goes away. Needless to say my eye is twitching as I write this and I wonder why people
don't have the ability to sleep half a brain at a time like so many other creatures. The benefits could enormous. You could be in a meeting and catching up on some shut eye. I think in this case evolution went backwards.