Randonneurs do it...Susan, my husband did 300, 400, and 600k rides this summer. The longest stretch of time he rode without any sleep was on the 400, for 23 hours and 43 minutes. Take heart---he always felt more energized and better when it got dark.
"My predominant feeling is one of gratitude. I have loved and been loved;I have been given much and I have given something in return...Above all, I have been a sentient being, a thinking animal, on this beautiful planet, and that in itself has been an enormous privilege and an adventure." O. Sacks