R, feel free to post additional information about the questions you find important or could help.
How much sleep is best for the human body to get per night?
Is it possible to get too much sleep each night?
It is relatively impossible to over sleep. For a normal person, their body will know when it has had enough sleep and feel well rested. People who sleep longer hours have shown to have reduced depression as well as being more productive and more imaginative during the day.
Science has yet to show any definitive answers of why we sleep but we do know some of the problems reducing sleep can cause. Many psychological disorders can be linked to sleep disorders and can be solved by either medication that mediates better sleep or by relaxation practices during the night time.
In a short way of saying it, too much sleep not scientifically a problem, as too little sleep is.