I remember as a child, my head would hit the pillow after a rigorous day going full steam, and it seemed I’d wake to daylight 3 seconds later, fully rested.
I think that’s natural for small kids.
I remember as a child nights that seemed to take three seconds, even though they were may 8 or 9 hours. Best sleep I ever had. I can sort of remember as it faded away. Probably in my mid-teens. I remember feeling melancholy that I didn’t sleep like that anymore. The very first time I took melatonin, I was about 42, and I seemed to sleep like that again for one night, and one night only. I was never able to replicate it.