If sleep wasn't very, very important our bodies wouldn't prefer 7-9 hours of sleep each day. I have a hard time believing long term sleep deprivation doesn't l

If sleep wasn't very, very important our bodies wouldn't prefer 7-9 hours of sleep each day. I have a hard time believing long term sleep deprivation doesn't lead to an early death. If lack of sleep makes it harder to stay slim, increases chances of dementia and diabetes well then these issues probably help shorten the life expectancy? I have a hard time believing this report.