Why We Sleep: Unlocking the Power of Sleep and Dreams by Matthew Walker is a book that explains the importance of sleep and its effects on the brain and body: 

• Sleep's benefits Sleep helps with learning, memory, logical thinking, and regulating emotions. It also helps with metabolism, appetite, and the immune system. 

• The effects of sleep deprivation Sleep deprivation can lead to a number of health issues, including an increased risk of cancer, Alzheimer's, and diabetes. It can also affect mood, memory, and bodily functions. 

• The role of dreams Dreams help to process painful memories and can inspire creativity. 

• How to improve sleep To get a good night's sleep, you can try to create good sleep hygiene habits, such as keeping your bedroom dark and cool. 

• The importance of sleep for society Sleep can help to improve the education and lifespan of children, and can increase the productivity and success of businesses. 

Matthew Walker is a neuroscientist and sleep expert at the University of California, Berkeley.