I still don't think details of a baby's sleep pattern are a matter of great security concern.
Not in and of itself, no, but OP eluded to a more enthusiastic litany of posts.
If the baby's full name, date and time of birth, hospital of birth
Given the description given, I wouldn't be surprised to find this information online.
home address, mother's maiden name
And these two are easy once you know your targets name, online contacts and hospital of birth.
... have also been revealed through various posts, then yes, that is a security risk.
But not how much it eats, sleeps, weighs and poos in the first six months of its life.
Unfortunately people tend not to limit their posts to what baby does. Baby has a name. Baby has a hospital visit. Baby has a granny. Baby if three months old today, etc. This is useable information if it is posted online.