Speaking from experience, when a person doesn't get enough sleep, their whole world becomes foggy and can cause them to make careless mistakes. As I am sitting here in a light, bright room in the middle of the afternoon, I am thinking of all the times I tried to carry on whithout sleep. I am also thinking of all the kids that stay up all night and go to school and pretend to be fine but in reality they are dragging. They are so tired they don't care, they fail, and I have heard of kids injuring themselves in sports.
Many years ago I worked the night shift and would come home only to find my mind still going and I felt the need to stay up and get things done, so I did. As the story goes on, I started noticing how I could not function. I couldn't even drive with out making careless mistakes such as not being able to stop very fast, or running a red light because it didn't register that it was red, or not seeing a pedistrian crossing the street. My eyes were fuzzy and I was just like a zombie in the drivers seat. I would fall asleep at work, I felt drained, my eyes burned, I felt like everything was buzzing. People would call my name and I wouldn't hear them at first. My performance at work started to decline and at that point I realized things needed to change. I worked things out so I could sleep during the day and within a week my outlook was much more focused and my normal happy friendly disposition returned.
If you are reading this and have experienced this yourself or with your kids, it's time to lay down the law and get some good uninterupted sleep. Your body will feel rested and things will be much better.