Although Santa works all year long in preparation for his delivery run throughout the world on Christmas Eve, he does get a bit worn out afterwards. With help from Father Time, he is able to slow down time in order to get all of his deliveries accomplished, but to Santa the time is like almost a week long of non-stop delivering of packages.
It is a great work out for him, and he looses a lot of weight and gets some awesome physical exercise. This is why all of the cookies really don't phase him much doing his deliveries since he pretty much burns them off before the end of the run.
Once he is done and safely back up at the North Pole, the adrenalin wears off, and he is able to get some real sleep and he needs to take a very long nap to get rested up. Sometimes these naps can last for a couple of days, but other times it can just be a few hours, depending on how the night went.
Each year, Mrs. Claus makes sure that his pajamas are ready and the bed is nice and comfy. She looks after him as he sleeps and makes sure that nobody bothers him until she makes the announcement that his is up form his nap.
When he awakens, he takes a long hot shower, gets dressed and has a very healthy and hardy breakfast. The next thing he does after that is he makes a visit with Dr. Twinklestein to have a physical to make sure everything checks out fine. Sometimes after that he gets back to work for a little bit, and other times he just heads back home to get ready for a much needed vacation with Mrs. Claus.