What would happen to a person if they didn't get the sleep they needed? Hedya, age 11, Australia

This is a really good question Hedya, because it makes us think about how important sleep is. Actually, sleep is one of the most important things we do.

While you were sleeping ...

When we sleep our bodies are really doing quite a lot of work. In the first few hours, we go into a very deep sleep. That's when our body is resting and repairing. It's when we fill up our energy stores for the next day.

At different times of the night, we also have a lot of lighter sleep. This includes something called "rapid eye movement" sleep or REM sleep. That's when someone's eyes flicker and move, even when shut.

During this type of sleep, we dream. Our brain is very, very active. It's busy sorting and organising information, storing memories and even working out problems.

So there's a lot of really important things that go on when we sleep.

Read more: Why do kids hate going to sleep, while adults usually love it?

So what happens if we don't sleep?

The first most obvious thing that happens when we don't sleep is we get sleepy. When we don't get enough rest, it's also harder to be active, want to do things, or get excited about things.

No wonder a lack of sleep can make us grumpy and irritable.

If we don't get enough REM sleep, it makes it harder to concentrate and learn. It makes it harder to remember school work from one day to the next. All these things make it harder to do well in school.

So having the right amount of sleep is really important.

Read more: Curious Kids: What happens to your brain if you don't get enough sleep?

How about if I have a few bad nights?

If we don't get good sleep on one night or two, we can probably catch up. Our bodies and brains will recover and we will be fine.

But if we don't have enough sleep or not good quality sleep for a long time, that's different. As sleep controls so many aspects of our health, this can really mess with our bodies and brains.

We are more likely to fail a year at school, put on weight, become depressed and get pretty sick for a long time, just to name a few examples.

So it's really best to set up good sleep patterns early in life so that doesn't happen to us.

Read more: Curious Kids: Do animals sleep like people? Do snails sleep in their shells?

How much is enough sleep?

Not everybody needs exactly the same amount of sleep. But people who study sleep, like me, think someone in your age group, Hedya, usually needs between nine and 11 hours a night.

We also need good quality sleep. This means it needs to be restful, without too much waking up at night. It also means we need to make sure we go to bed and wake up around the same times every day.

Hello, curious kids! Do you have a question you'd like an expert to answer? Ask an adult to send your question to curiouskids@theconversation.edu.au

Author: Sarah Blunden - Professor and Head of Paediatric Sleep Research, CQUniversity Australia