My circadian clock is finely tuned. You don't mess with a man's circadian clock.
You know who else's circadian clock you can't mess with?
Infants' and toddlers' and preschoolers.
We had both grandsons this weekend, but not at the same time. The toddler was Friday and Saturday night- you couldn't tell him Sunday morning he got up at 5 AM and it was too early.
We had the preschooler last night. He came strolling into our bedroom just before 6 AM, wondering why on earth we were still in bed. It was "his" 7 AM, and he was raring to go. By "our" 7 AM, he had eaten, changed into his play clothes, and was ready for the day. He ended up going grocery shopping at 7:15 today with Bob, since he was more than ready for going out. And there is no way on God's green earth he will be able to stay up until 8 PM tonight for his mom. So she's in for a pre-6 AM morning as well.
Leave the clock alone already!