So sleep impacts all aspects of development.
So learning, children who are not sleeping well have difficulties paying attention in school, have difficulties processing or remembering information. So it's important to get enough sleep for children to learn.
Mood, if children aren't getting enough sleep, it's going to affect their mood which can impact their interactions both with their family as well with their peers. We know that when children sleep, growth hormone is released. So if a child has a sleep disorder like sleep apnea or a child who's not getting enough sleep, they may not be getting sufficient growth hormone released during sleep which may impact growth and development on a physiological level.
We also know that sleep is very important for immune functioning. So children who aren't sleeping as well, it may impact their ability to fight off the common cold or stay healthy during the winter.