A good night's sleep is just as important as regular exercise and a healthy diet. Research shows that poor sleep has immediate negative effects on your hormones, exercise performance and brain function. It can also cause weight gain and increase disease risk in both adults and children. In contrast, good sleep can help you eat less, exercise better and be healthier. Over the past few decades, both sleep quality and quantity has declined. In fact, many people regularly get poor sleep. If you want to optimize your health or lose weight, then getting a good night's sleep is one of the most important things you can do.