Have you ever stayed up late.9 If so, you know that not getting enough sleep can leave you tired and grumpy (脾气暴躁的). Not sleeping enough can also make it harder to think clearly the next day. Sleep experts have long known that getting a good night's sleep is important. It helps kids perform. their best during the day. A recent study shows that sleep helps improve problem-solving skills and creative(创造性) thinking. For the study, two groups of volunteers answered a math problem. The group that slept for eight hours solved the problem correctly more often than the group that did not get enough sleep. While you sleep, your brain is busy doing its' homework'. It sorts out information from your day. Getting enough sleep each night can boost your brainpower. That will help you do your best in school. Experts say that, in return, can lead to better grades. What is the best title for the text?