The German philosopher Arthur Schopenhauer knew many 100 years ago that we humans need sleep to gather energy and restore strength to our bodies.
Because there is a lot going on in the body while we sleep: The brain stores and processes the impressions of the day, the metabolism works and fills the energy stores, the immune system is strengthened and the cardiovascular system can recover.
How much sleep we need is individual and different for each person. How much sleep do you need to feel fit and well the next morning?