DC Days 2 and 3 as well, I should imagine.
DC Day 1
You could always tell folks it's all about following the advice at 1 Cor 16:19-20:19
Do you not know that your body is a temple of the Holy Spirit, who is in you, whom you have received from God? You are not your own;
20you were bought at a price. Therefore honor God with your body.
And the Washtowel Slaveholdery even acknowledges this effect: The Feb 8, 2004 Asleep! had an article about sleep deprivation. Too bad that was the showcase: The same month, there was the Kingdumb Misery article about getting up in time to be at the Kingdumb Hell at 5:30 in the morning to do street work.