I work with students who often do not go to bed till 3, 4, or perhaps never made it to bed the night before. They arrive yawning and by lunch, they've placed their heads on the table and are sound asleep.
I've seen students so tired, they slept through the bells ringing and the changing of classes. Why does this happen? Lots of reasons from alcohol, to fighting, to no one making sure they have gone to bed.
I'm sure many of you have the same happening at your school. The students assure me they don't need much sleep but I know a lack of sleep can interfere significantly with learning. There are two areas in which a lack of sleep can be detrimental to learning. First, it can make it difficult for a person to focus on the material and learn it effectively. Second, sleep gives the brain time to process information.
The lack of sleep can leave your brain feeling foggy, messes with your judgement, and it interferes ith your fine motor skills. In addition, it can put you at risk for certain health issues such as diabetes, obesity, and other diseases.
As for your memory, scientists believe sleep is needed so the brain has time to consolidate information. It is believed that the hippocampus and neocortex are the actual parts of the brain involved in the process. While you sleep the hippocampus relays the events of the day (including what you've learned) to the neocortex where these memories are reviewed and processed and stored as long term memories.
In addition, it appears that some memories become more stable during REM (Rapid Eye Movement), while other memories become more secure during deep sleep. Sleep allows your brain to sort through memories to determine the important ones and strengthens information.
Apparently when you sleep, your brain cells shrink some to allow fluid to flow around and between the cells. The fluid washes out toxins and cleans it up so you can think better. Furthermore when you get enough sleep your ability to tackle harder problems and understand problems increase.
One reason it is good to go over material before you take a nap or go to sleep for the night increases your chances of dreaming about it. When you dream about the material, it helps you understand the material better and remember it better.
So anytime you have a teen who tells you they do well on 3 or 4 hours a sleep each night, let them know how more sleep will help them in school.