To vitalize is to enliven or excite. There's nothing like a good night's sleep to vitalize a tired child.
You can use the verb vitalize to describe what happens when you become energized or perked up: "My tai chi class isn't great exercise, but it does vitalize me." A much more common, and related, word is revitalize. For some reason, vitalize is rarely used, although it's much older, first used in the 1670's, while revitalize didn't come into use until 1858 — almost two hundred years later.