You don't really make a switch from being a night owl. I thought I'd made switches multiple times too:

* Taking early classes in college * Deliberately cooling myself down and going to bed super early * Getting a puppy that forced me to wake up super early

Every single method regressed to night-owl schedule within 2 months. Not to mention my productivity and learning ability took a nosedive during the periods I was waking up early.

This is over a period spanning 15 years, so it involves multiple stages of life as well.

Agreed. At 46, and having been a night-owl pretty much my entire life, I'm skeptical that you can just "switch" to another mode. Maybe you can, through very conscious and focused effort, manage to adapt to what appears to be a "morning person" lifestyle; but I suspect that people who do that are ultimately just faking it.

That said, I've never looked at being a night-owl as something that needed to be "fixed" or something that I'd want to change.

When I had to wake at 4:30 for work, I hated it. Now that I don't have to go to work so early, I love getting up early, because those first couple of hours are my most productive. There are zero distractions and my mind is fresh from a good sleep. I'd rather have these most productive hours for myself, whereas when I was getting up and going straight to work, I'd only have the evening hours where I was already exhausted after working 13 hours.

I'm almost certain I couldn't do it without the proper diet and exercise though. If I let go with the diet or stopped going to the gym, I reckon I'd probably slip back to becoming a night owl, and become more lazy too.

It does mean that I'm tired by 11 or midnight, but even when left entirely on my own schedule (kids away on school vacation), my "new" natural schedule persists.

I didn't seek to change it (and if it drifted back later, I might even be slightly happier).

May not work for everyone...

Time will tell.

Or running civic services 7 AM - 3 PM which makes it impossible to schedule without a free day or understanding boss. Something that should be available with perhaps only a minor downtime works only for a few hours.

The cumulated morning/evening hours tend to overload transportation facilities too.

I've noticed it already in my 30s, I can no longer sleep in so easily and have to get up, even if I'm tired.

Unfortunately it is because older people tend to have poorer sleep quality in general (less time in deep sleep cycles) so that's a pretty big downside.

I really did force the change for myself and it totally sucked going through it. I still don't just jump out of bed and feel instantly great. It takes 30 minutes or so to get fully awake. For example, this morning I so did not want to get up because I stayed up until 1 am. However, I did get up at 5:30 am anyway. It was awful and I'm dragging today. Caffeine helps as well.

I work for a transportation company and there are a lot of field people that have moved in to c-level positions and have the "butts in seats" mentality and I think that's why after 12 years of 9:30 - 10:00 am starts, suddenly I get smacked with a "needs improvement" on my review. And our technology department is having big problems retaining talent.

I tried a bunch of things, but eating at the right time helps.

If I eat too close to bedtime, I think my sleep is initially ok (food makes you sleepy), but it's possible it disturbs my sleep or I get acid reflux or something.

If I eat too far from bedtime, I wake up I suspect because my blood sugar is low -- and of course the body produces adrenaline when that happens.