system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: What happens to my brain if I don´t get enough sleep?
gpt
The brain does a number of things while sleeping, which I'll list below. (Note: The study of sleep on the brain is kind of non-conclusive, these are the best academic OPINIONS of what happens.)

1. It records the events of the day into your brain, essentially 'creating' memories. [No sleep - No recording/incomplete recording. You are more likely to forget things you learned/did.]

2. The brain rests various connections that are in constant use during the day. It's a muscle and like muscles in your arms and legs, can be become so strained that it fails to function properly (like when you've been lifting things all day and get to the put you can't do so anymore). [No sleep = Slurred/mismatched speech, failure to interpret what is going on around you, slowed reaction times.]

3. Following up on the previous point, your brains constant activity for over 24 hours will overwork it to the point signals become crossed. You may hallucinate because your brain expects something to appear that won't, you may take risks or indulge because your brain isn't getting through the proper cautions it normally does, you may day dream at inappropriate times and suddenly be hungry because the ability to time these things appropriately isn't getting through.

4. Brain Damage. In the long term and with repeated behavior, your brain cells may break down from constantly being overworked. The same concept is in all your muscles, work them too hard and they will become damaged.

To sum it up, your brain is like a muscle. All the same things that happen to you when you overwork your arms/legs/abs/back will happen to your brain. It will get strained and it will get damaged. You will 'pull' it, but given it's sensitive nature, unlike your arms or legs, the damage won't just repair itself.

Edit: I'd like to also mention that everyone's biology is unique and what may work for other people may not work for you. There are reports of people who need little/no sleep and live there lives as normally as you and I. There are also reports of people who have died of exhaustion from getting no sleep at all after a short while. Everything we know about why we need sleep at this point is theory based on educated assumptions and what little we do know about how the brain works.