The time that the average 8 year old goes to bed is between 7:30 PM to 8:00 PM on school nights and when out of school or on weekends the average 8 year old goes to bed around 9:00 PM to 9:30 PM
8 year olds should go to bed by 8:00 PM to 8:30 PM on school nights so they have enough time to get enough sleep before they wake up for school the next morning.
On weekends they can stay up till 10:00 PM to 10:30 PM
8 year olds need at least 9 to 11 hours of sleep to stay healthy and function the next day.
8 year olds typically go to bed between 7 p.m. and 9 p.m. and wake up between 6 a.m. and 8 a.m.
Children at this age typically go to bed between 7 p.m. and 9 p.m. and wake up around 6 a.m. and 8 a.m., just as they did when they were younger.
By five years of age, most children no longer need naps, with less than 30% of children that age still taking them.
The number decreases even more by age six, where less than 10% of children nap.
Nearly all children stop napping by seven years of age.
Unless your child is reliably capable of sleeping in for a few hours in the morning, letting them stay up late means they're not getting the amount of sleep they need.
I firmly suggest that kids over the age of three should still be getting a minimum of 11 hours sleep a night.