I have no idea what little sleepies is

Hi, this page keeps coming up on my feed as something I would be interested in (???). I have no idea what the little sleepies lore is or why there is so much snark. But these posts with the old ladies in kids pajamas kills me every night when I doom scroll rocking my kiddo while he sleeps.

Can someone explain like I’m 5 years old what little sleepies is