Jack has a cold, and Thursday night he was up in the night 2 or 3 times (we couldn't remember the next day). His schedule for Friday:
5:20 -- up for the day
11:20 -- nap
12:50 -- up from nap (painters were scrapping the windows outside his room)
8:30 -- to bed
Hans and I were dragging all day (and I caught Jack's cold), but Jack was pretty much bouncing off the walls as usual, until we lured him to bed with his train stories. Being sick or lacking sleep does not seem to affect him. He doesn't "catch up" at all.
Thankfully, last night he slept from 8:30 to 6:15. His nose is still runny, but he's not coughing or feverish. And the painters are done with our house!