It sounds like you may have delayed sleep phase disorder -- basically, a late-shifted circadian rhythm. I keep similar hours by default and was diagnosed with DSPD about 5 years ago. It explained a lot of issues in my life and was a relief to hear that I wasn't just "lazy" like all the morning people always told me!

As an additional plus, if you are in the United States, sleep disorders qualify as disabilities, which means employers are generally required to make reasonable accommodations, including later working hours. I find that tech companies are generally fine with varying hours anyway, but it's a nice tool to keep in your back pocket in case you have a manager that insists on 9am meetings.