As soon as you are tempted to close an eye, even "for just a second", find the nearest safe place to pull
over and take nap!
Other symptoms to watch for:
Inability to maintain a desired speed. If you find yourself slowing down and constantly having to speed
back up, you are ready to fall asleep!
Forgetting to turn high beams down for oncoming traffic.
Indecision. Can't decide to stop for gas or continue? Can't decide what turn to take? These are all a result