How do you temporarily break a sleep cycle?

Factual Questions
1

With only a few exceptions I get up for work at 8:30a.m. every day. The exception would be on days when I need to get up earlier because I have to travel, but 99% of the time it’s 8:30. I’m usually in bed by 1:30 a.m…

The problem is, as has probably happened to most of you, is I’m in this set cycle, and can’t break out of it on days I don’t need to be up so early. Weekends, days off, vacation days, whatever. I took the day off today because I was going to take my wife to the doctor. Her appointment wasn’t until noon, which ment I could sleep until at least 10. I even stayed up until 2:30 last night, but damn it, even with no alarm clock I still woke up at 8:30. And I couldn’t get to sleep, which is what happens to me on weekends too. Every sunday I find myself awake at 8;30 when i wanted to sleep until noon. This wouldn’t be a problem if I could get back to sleep. But I lay there for over an hour and then say screw it. There was a time when I could sleep 12 hours straight. No more! And it sucks.
Any techniques out there you guys know of?

2

I don’t usually advocate drugs, but stuff like Benadryl or maybe that melatonin might work. When I have to switch working on east or west coast, I try to sleep earlier or later for a few days, & that works for me. Hmm. I could probably sleep 12 or 14 hours straight if allowed.

3

Well, the obvious ones are drink and drugs. Staying up late might throw you off, but I doubt it. Making sure the curtains are closed/wear a mask.

When I was at school and had to get up early to finish an essay, I would go to sleep repeating the time I had to wake and how long that gave me to sleep. I’d wake up 2 minutes before the alarm, almost without fail. Now, I know I was using this to wake up earlier than I would normally, but if you replace the sense of urgency with a relaxed feeling, it might work.

So, maybe some sort of meditation?