When my son was born we tracked his intake and output with an app. In baby classes they tell you to track this stuff for several days after birth as a kind of health barometer. We started an didn't stop for the first year. Diaper changes alone revealed some interesting patterns.
We didn't get many stealth diaper changes in. Blank areas match his sleep schedule incredibly well:
no regular sleep pattern, followed by sleeping through the night, followed by morning naps
disruptions in his sleep pattern due to travel during the winter holidays, which was also teething time 🙃
A newborn's stomach is so small that it barely holds any liquid, but they're growing and hungry all the time. This leads to a tough cycle for caregivers where you're either feeding, changing, or hoping they sleep at any given 30 min block for days/weeks/months on end. We were lucky that he was healthy, and this was all we had to grind through. Others have reported similar trends.
We never tracked his sleep directly, but changing ~10 diapers a day yields a sufficient sampling rate to reveal other patterns. Cool!
All credit goes to my wife for tracking this manually for a whole year. Normally I'm the obsessive nerd, but she persisted despite me telling her it wasn't worth her time. I'm glad I was wrong.