Optimal sleep duration 4.5 to 6.5 hours?

The claim that everyone should sleep eight hours a night for a normal and healthy life has now been refuted by various recent studies. 

A study by the University of California in San Diego even named a period of just 5 to 6.5 hours as the optimal sleep duration for an adult. 

In the study, which focused primarily on the connection between sleep duration and life expectancy, the test subjects who slept for the specified duration had a much better survival rate than those test participants who slept shorter or longer. 

As a result, people who sleep less than eight hours do not have to worry about their health. On the contrary: According to the latest scientific findings, a sleep duration of five hours can even be conducive to a healthy and vital life.

Another study concluded that 4.5 hours is sufficient

The experts found that people who slept less than 4.5 hours a night, and those who slept more than 6.5 hours each night had a greater risk of cognitive decline over time.

According to Trump, he gets by with four hours of sleep. His counterpart, French President Emmanuel Macron, only needs four hours of sleep. 

The Rock says he sleeps only 3 to 5 hours a night

From Napoleon Bonaparte comes the bon mot: "Man sleeps four hours, woman five, six an idiot."