Exactly. At late nights when I am unsure about whether to sleep or continue working, I simply go to the site and calculate when to sleep. It has become a habit!
I'm completely amazed that people do this to figure out when to sleep. My intent is not to sound rude; I'm a big believer of "do what works" in my personal life and at work. For me it's always so simple: if the following day is a work day, I need to make sure I get at least 7 hours of sleep so that determines how late I can stay up. If it's the weekend, I go to sleep when my body says it needs a break.