From WiseBrother.com:
Here's something else we've been doing wrong our whole life. You're probably using ANTIPERSPIRANT incorrectly. You should really be putting it on at NIGHT, not in the morning. Here's why . . .
First, we're only talking about antiperspirant, not deodorant. Antiperspirant plugs your pores and prevents you from sweating. Most deodorants just mask the smell of B.O.
So why at night? It's because your body temperature drops while you're asleep, so you sweat less. And sweating too much can prevent it from doing its thing.
Basically, putting it on at night gives your skin more time to absorb the active ingredient, usually aluminum. And most antiperspirants are designed to work for 24 to 48 hours. So it'll still work fine the next day.
Showering won't wash it off, so you can still shower in the morning. And depending on how much you sweat, you might not even need to use it every day.
If you're a deodorant person, here's another tip: You shouldn't put it on right after you get out of the shower.
Deodorant is meant to be used on skin that's totally dry. So it works better if you wait until your pits have aired out, and there's no moisture at all.