There are genetic programs that take off when you get a child, even as a father (not sure what your gender is). It was shown in voles:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6305489/

Fish too:

https://doi.org/10.1038/s41467-019-12212-7

Kind of same here. I start functioning at 7 because the world doesn't care i need these these two hours. I still rarely fall asleep earlier than 12PM, and it takes perhaps a week for the lack of sleep to accumulate so i crash with a migraine at 9 or 8 PM. I love my kid but sleep is a fuck.