I'm new to the series, and I was wondering if you would be so kind as to explain the benefit of sleeping in Skyrim?
In Skyrim you get a "well rested" perk if you sleep for a few hours. Not sure what the minimum is, but I think it's more than 4. Depending on the type of bed you sleep in you may get better perks. For example, I slept in some rickity bandit bed in a fort and got "rested", but sleeping in a comfortable inn got me the "well rested" perk. I believe there are other perks dependant on if your sleeping with your spouse or whatever, but I haven't had that yet,
Why would I want to level up whilst sleeping/after sleeping?
That's going back to Oblivion, where you had to sleep in order to be able to level up (rest and meditate on what you have learnt). In Skyrim you can level up on the fly so sleeping isn't as striclty neccessary as it was before.
Personally I sleep for 8 or more hours most nights unless I'm travelling and can't find anywhere to sleep and so travel through the night. It's part practicality (I don't like moving around at night incase I miss something), and part role-playing, I sleep when it's dark, adventure in the day etc.