Less sleep is harmful to health?

Numerous studies over the years have linked inadequate sleep with increased risks of chronic diseases and mortality. For example, a review of 16 studies with over 1 million participants found those sleeping 5 hours or less had significantly higher rates of heart disease, strokes, and premature death compared to those sleeping 7 to 8 hours nightly. Likewise, another study of 500,000 adults showed people regularly sleeping 6 hours or less were 12% more likely to die prematurely versus those sleeping 6 to 7 hours.

Many studies over time link inadequate sleep to higher disease risks and death. For example, a review of over 1 million people found those sleeping just 5 hours had more heart disease, strokes, and early death versus people getting 7-8 hours. Another study of 500,000 adults showed short sleepers were 12% more likely to die early than those sleeping 6-7 hours.

Experiments restricting sleep to 4-6 hours nightly also caused issues. These include worse immune function, focus lapses, increased stress hormones, appetite changes and weight gain, and higher blood pressure when healthy adults got insufficient rest.

So evidence indicates not meeting the recommended 7+ hours of sleep appears unhealthy. However, not everyone needs exactly 7-9 hours. Sleep needs vary slightly between people based on age, genes, etc. Some thrive on 6 hours. Others require 9 or more. The key is getting the amount your body needs to prevent a deficit.

For most adults, 7-8 hours nightly is ideal. This amount links with many benefits: better memory, cognition, immunity, emotional health, heart health, metabolic function, and longevity. Those consistently getting sufficient sleep have lower obesity, diabetes, blood pressure, and inflammation too.

In conclusion, research generally shows not getting ~7 hours sleep can indeed harm adult health. The exact sleep need differs individually. But regularly getting much less than 7 hours likely raises risks of diseases, cognitive impairment, and early death for most people. So getting adequate quality sleep based on your body’s needs is key for overall health.