Babies and young children sleep a great deal but they are in an accelerated growth period.
Adults are different.
I have a depressive personality (we will now pause while everyone I have interacted with on FR for twenty years indulges in a sarcastic Nooooo really?) One thing I notice is that when I start sleeping more then ten hours I am sliding into the gray and it is time for me to do something about it.
Sometimes I think, ‘what’s half a day if I’m rested.’
Sleep keeps me from being depressed.
I’ve been known to sleep 12 hours a day. In fact, I lost weight that way. Less time to eat.
The times that I am awake, I am productive, always on the move, usually outside. I run hard. I sleep hard.
When I was a child, my parents would never let me get enough sleep: insomnia, especially if Dad fell asleep before me because he snored. I am very protective of my sleep. Just me.
Likewise. I supplement vitamin D3 and use a 'happy light' through the dark season. It helps a lot.