Sleep
It is essential that children get enough sleep. Children need sleep in order to grow and develop normally and to concentrate on learning at school. There are many reasons why children may not get enough sleep and there is plenty of advice out there. Below is a website that you may find useful.
https://sleepcouncil.org.uk/getting-a-good-night-sleep-for-children/
There is also excellent advice on the NHS website, just google: NHS sleep problems in children.