You've heard that you should get eight hours of sleep per night, a whole industry has built up trying to help people who can't do that, but like BMI, organic food, and 'alcohol in moderation is okay', there is no science to it.

A healthy amount of sleep is instead cultural, which may mean it is geographical. Japan is considered a healthy society but they only average  six hours and 18 minutes per night while Canada is seven hours and  27 minutes and in France it is seven hours and 51 minutes, but an analysis of sleep data and health outcomes for nearly 5,000 people in 20 countries found not getting 8 hours of sleep isn't making a difference. Which means any chronic lack of sleep may be an effect and not a cause.



Some epidemiology papers have linked shorter sleep durations and poor health outcomes but this group wanted to investigate whether people from countries with shorter sleep durations suffer from worse health. There was no evidence that people in countries with less sleep were less healthy than those in longer-sleeping nations.

The only thing that correlated to positive outcomes was sleeping closer to norms of your community. Obviously, since this is a statistical analysis it is in the EXPLORATORY pile like all epidemiological claims are until science verifies them

The researchers also found that in all 20 countries, people appeared to be sleeping at least one hour less than what was considered optimal by their culture, similar to how the USDA pyramid recommendations are aspirational and only 2% of people can actually eat that way.

As in all cases, unless science has determined that harm exists, such as smoking cigarettes or alcohol, public health guidelines should be tailored to fit the cultural norms of different populations. You won't get better outcomes making people feel like there is something wrong with them, that is just the pathway to more pharmaceutical ads.