Passage Four
Many adults in developed countries don't get the recommended seven to nine hours of sleep per night, which can have serious health consequences. Sleeping less than six hours a night can weaken the immune system, increase the risk of certain cancers, and is linked to Alzheimer's disease. Just one week of insufficient sleep can disrupt blood sugar levels, leading to pre-diabetes. Short sleep also raises the risk of cardiovascular diseases, stroke, and heart failure.
Sleep deprivation can also affect appetite, increasing hunger and decreasing feelings of fullness, leading to weight gain.Dieting without enough sleep is futile(无效的),as the weight lost is often from lean body mass, not fat. The shorter your sleep, the shorter your life span is likely to be. The saying "'ll sleep when I'm dead" is not just an expression - it reflects a harmful mindset that can lead to a lower quality of life and even an earlier death.
The Center for Disease Control has recognized insufficient sleep as a public health epidemic, and for good reason. The countries with the most significant decline in sleep duration over the past century are also those experiencing the highest increases in physical diseases and mental disorders. This correlation suggests that our collective sleep habits are taking a toll on both individual health and societal well-being.
Scientists are urging medical professionals to prioritize sleep as part of their health advice, advocating for a shift in how sleep is viewed and prescribed within the healthcare system. The prescription for better health may be as simple as getting a good night's sleep. Unlike sleeping pills, which come with their own set of health risks, natural sleep is a safe, enjoyable, and cost-effective remedy that can significantly improve health outcomes and reduce the burden on healthcare systems.
【问题】What is the main theme of the passage?