It can be hard getting the kids to bed sometimes, but new research has shown just how important it is for them to get a good night's sleep.
The Sleep Council claims that more than 90% of the primary school teachers it polled said children struggle to give lessons their full attention because of tiredness.
If you're constantly trying to get your kids to turn off their games console then you won't be surprised to hear that the majority of teachers think video games and TVs are keeping kids up.
Many also think that mums and dads aren't strict enough when it comes to going to bed, but what do you think?
The poll was conducted to coincide with the Better Brains With More Sleep campaign, part of National Bed Month.
Perhaps unsurprisingly, more than 50% said that children who slept best were among the brightest.
Some 250 teachers were asked for their opinions on kids' sleep.
Jessica Alexander of The Sleep Council said: "As part of our project we wanted to establish just how much of an issue lack of sleep has become among young school children. Even we have been taken aback by the sheer scale of the problem."
Sion Humphreys, policy advisor for the National Association of Headteachers, said: "Schools cannot succeed without effective partnerships with the home. A tired and irritable child will not thrive, particularly in the active and pacey modern classroom."