Question: What happens to your brain when you are sleep-deprived?

Rebecca Dewey answered on 16 Jun 2015:

This is a tricky one – on the face of it, not a lot happens to the brain during sleep deprivation – the brain won’t look very different. But it’s *what the brain does* that’s different. So there are many different chemicals that help transport messages from one part of the brain to another (called neurotransmitters), and some of these gradually increase as the time since sleep increases, whereas others may decrease as the time since sleep decreases. It’s these levels of neurotransmitters that affect what areas of the brain are used in doing a task, and at what point during the task they are called on to act. For example, if someone is sleepy, and they are trying to (for example) do a crossword or a puzzle, a lot of the “frontal areas” (i.e. areas towards the front of the head, that are most associated with thinking and cognitive processing) will be more active, because they are having to work harder to do even quite simple tasks. Whereas sometimes language areas, which are further out towards the sides of the head, in the “temporal lobes” will be less active, or not active at all because the neurotransmitter levels haven’t allowed them to get involved. These neurotransmitter levels reset themselves to “normal” (whatever that is) during sleep, which is another reason why sleep is so important.