This was what did it for me as well. I was alone with my three kids (5,6 and 9) for half a year recently (wife went on a foreign student exchange program) and to prevent life from descending into chaos I established a pretty dictatorial parenting style. Kids were asleep by 8-9pm, and we had to be up at 7am to prevent our mornings from being stressful. I eventually discovered that I could make much better use of the day if I also went to sleep early and woke up about 5am to prepare the day or start working. These early hours were much so much more productive than the evening hours.
I've tried to stick with this program, or at least a version of it, but ironically it's kind of harder now that there are two of us again.
I regualrly slept between 1-3am for many years. After having a baby (6 month old), I'm ready to sleep whenever, and definitely can't stay up past 11. Huge win in terms of sleeping early and waking up early.
Just FWIW this doesn’t always work. I’m more of a night owl, and having kids didn’t flip my schedule, it just left me really exhausted. My wife and I ended up working out a sort of arrangement where she usually goes to bed earlier and gets up earlier, while I stay up later and sleep in more. When our kids fail to sleep through the night, it’s often a wake up around 11-midnight where they want milk or need to use the bathroom or something, so since I’m still awake I can field those without my wife having to wake up. Thus it works okay, but it’s not perfect.
I dunno if this is hyperbolic, but having a baby to fix a sleep schedule seems like an insanely complicated solution that carries a lot more side effects to a fairly trivial problem.
Although I wake up for work every day and live the early bird schedule, I am a night owl. Every so often my body will reject the schedule and I wake up between midnight and 1:00AM. Of course I am sleepy by sunrise but I have to push through the day to get back on schedule.
Yeah sure, this happens to me as well. I just woke up at 3:30 today, squeezed a few oranges and played the guitar for an hour like it was the middle of the day.
And if for some reason I'm home alone for more than a couple of few days I'll revert to my schedule of sleeping early in the morning.
But my point still stands, I can adhere to my new schedule pretty effortlessly when the situation is right.
Which makes me personally question how much of being a night person is nurture.
Most of the night persons I've encountered have a pretty consistent schedule of staying up at night, which isn't what should be happening if they fit the profile of the kind of person that the linked study examines.
A person like that should have, when situations allow, no schedule because they function on a non-24-hour cycle.
I made the swap too. As an individual contributor I wanted to work until everything was finished. When I moved to managing managers I wanted to get ahead of the day, and be current before everyone else started.
I was the same for many years then travelling from Chile to Peru, there was a two hour time difference, despite being pretty much the same longitude (there was a one hour difference, and I think Chile had daylight savings on top of that).
It made me realise that it's all just a number. In other words if you don't like getting up early, then go to bed an hour or two earlier. It has exactly the same effect. In countries with daylight savings we adjust our schedules by an hour two times year and no one makes much of a big deal. Its the same as that!
I think we perhaps need some info on the sex of, and level of responsibilities of, the people claiming to be cured by having children.
[Father's testosterone levels drop considerably starting a little prior to birth of their children (and when taking on care of young children) reportedly. Mother's hormonal changes go without saying, I feel.]
Just FWIW none of my well-spaced in age children fixed me. But having a fluid sleep cycle often meant I wasn't bothered. Sometimes I'm super awake at 4am, sometimes 6am, sometimes I'm ready to crash by 4pm, sometimes by midnight.
What killed me was having to work a second job during the night-time with our first kid, not fun.
In short, still broken sleep cycle, almost exactly like my mother has been through her life AFAICT.
Now I wake up by 7 before my alarm even rings.
All it took was getting into the habit of trying to get a little person to sleep by 10 in the evening and falling asleep with them.
I'm still at my most productive at the end of the working day however and early morning is still not great.