With children returning to the classroom this week, it can be tricky to get them back into their term-time routines after a summer of relaxed bedtimes and lie-ins.
To help parents understand the best time for kids to go to bed - based on both their age and the time they have to get up in the morning - one school has posted a mega useful chart.
Wilson Elementary School in Wisconsin, US, shared the visual to help parents of children at their school, but it's actually gone viral internationally thanks to hundreds of thousands of shares.
"It's taken this school by storm - and more so, because barely 200 kids attend here and this chart suggesting what time your child should go to bed has been shared on Facebook more than 300,000 times," Stacy Karlsen, first grade teacher at Wilson Elementary School told Fox6News.
"Initially i just said to my principal 'you have to be kidding me.' To me, it was a shock. I didn't make it up. I found it coming across my personal page and I thought 'wow this is super helpful'."
Meanwhile, principal Yolanda Jackson-Lewis added: "It was crazy. I had to come back to my office and go to the Wilson Elementary School Facebook page to see it for myself.
"We can tell who's well-rested and ready for their day and those who maybe didn't get enough sleep the night before."
The chart claims that kids aged five should be going to bed between 6.45pm and 8.15pm depending on the time they're getting up in the morning.
As the child's age increases by one year, the bedtime appears to get later by 15 minutes, until the child is aged 11. For those aged 11 and 12, the bedtimes vary between 8.15pm and 9.45pm.
According to information circulated by Great Ormond Street Hospital, children of different ages need varying hours of sleep.
They advise infants aged four to 12 months should be getting 12-16 hours. Meanwhile those aged one to two years should get 11-14 hours of shut eye while those between ages of three and five should have 10-13 hours of sleep. For these age groups, the hours indicated include both nighttime sleep and naps.
Children aged six to 12 years should be getting 9-12 hours and teenagers 8-10 hours.