It can leave you grumpy and distracted the next day, making it hard to focus. But long-term sleep loss is linked to dementia, heart disease, diabetes, and obesity. You can also add problems with your immune system, depression and anxiety, and ongoing pain to that list. Adults need anywhere from 7-9 hours of shuteye a night. Kids and teens need even more. Talk to your doctor if you have trouble getting enough sleep. Treatment may help. It might include lifestyle changes, medication, talk therapy, or a mix of all three.