All of a sudden, for the last few nights, my puppy wakes up at 11 p.m. and won’t go back to sleep. I made a point getting him plenty of exercise to wear him out today, but nope! Like clockwork, he slept from his normal bedtime of 8 p.m. and whine-bark-whine cranks up at 11. He’s standing in his crate giving me this baleful glare. He’s been sleeping comfortably in his crate all night for months. I’d have to coax him awake for a pee break in the wee hours, then out like s light. Now he develops an antipathy to sleep?!? He’s 7-1/2 months old. Is this a “teen” thing? By the way, I didn’t force a circadian rhythm on him. He came to me with an 8 p.m. to 6 a.m. sleep cycle.