What happens if you don't get enough sleep? For one thing, you'll be pretty grumpy. Missing sleep can make you clumsy, too. you are more likely to drop things or trip over your own feet. You won't be able to think as well, either. Even simple tasks are difficult for a tired brain. It you don't get enough sleep,you won't be at your best. If you want to have a good day, Start whit a good night's sleep.