Most people need a swipe or two of deodorant to keep them fresh throughout the day. Because deodorants only mask odor, people looking to reduce sweating should actually apply antiperspirants. What most people may not know, is that the time you actually apply your antiperspirant can make a difference.
Apply at Night
Surprisingly enough, applying your antiperspirant at night is more effective than swiping it on when you first wake up in the morning. At night, your body temperature is cooler, which means you sweat less. While you doze, your sweat glands are therefore more receptive to the active ingredients in antiperspirant, helping it to penetrate more effectively.
Problems With Morning Application
During the morning, not only is your sweat rate higher, but you've also likely just gotten out of the shower, which means your armpits won't be as dry. When skin is wet, the chemicals that actually prevent sweat will be blocked from seeping into the pores, meaning the sweat-blocking reaction will actually happen on the outer-layers of the skin instead.
Re-applying in the Morning
According to doctors, there's no need to reapply antiperspirant in the morning. If you want to, it won't hurt anything, but it probably won't make much of a positive difference, either. Antiperspirant can actually still work after showering and possibly even for a few days after application.
If You Don't Sweat Much
That trick is especially beneficial for people who perspire a lot and use antiperspirants instead of deodorants. If sweating isn't much of a concern for you and you can't remember to apply antiperspirant at night, applying it during the day should be fine. But, if you're looking to sweat less, swipe on antiperspirant right before you go to bed and see if it makes a difference.