Regarding the first night of Shavuos, the Arizal writes “Know that one who does not sleep at all this night, but instead spends all his time learning Torah, is guaranteed that he will live out the year and no harm will befall him.”
This year, with Shabbos preceding Shavuos, it is a wonderful opportunity to take a nap and be better equipped to learn the entire night. This statement and guarantee by the Arizal should not be taken lightly. But in order to get this guarantee, a person has to spend “all his time learning Torah,” – which probably means without taking a break and talking to friends. We are all capable of this. If you try to do this, Hashem will assist you and make it happen. Haztlocha!
Emuna Daily 
Just a brief reminder that preparing on Shabbos for after Shabbos is halachically problematic. One should ask a competent halachic authority as to how to do this practically.
Rabbi Aaron Glatt told me the following:
Bottom line – don’t say aloud – “I am hereby now napping to prepare for motzei Shabbos” but one can certainly nap with the full intent that he is doing so to stay up better motzei Shabbat / leil Shavuos.