Hey there,
Babies don’t really sleep as their circadian rhythm isn’t really established yet. If you observe baby closely, even during these short naps, they experience rapid eye movement under their eyelids. This is also the very thing that prevents SIDS from happening as some babies can also forget to breathe.
Quite like this article:
https://www.google.com.sg/amp/s/amp.firstfiveyears.org.au/child-development/baby-wont-sleep-heres-why-babies-wake
Hope this helps