Eradicate the Odor
Most people shower to remove or prevent body odor. That odor is produced in part by sebum, an oil the skin manufactures to keep it moisturized. When you shower, you remove the sebum from the skin—along with all the dirt it can collect. Hot showers further strip the skin of sebum, dirt and potentially offensive odor.
“That’s why people are inclined to shower more frequently in summer,” when sunblock and sweat may add to that tacky, dirty feeling, Dr. Ogunleye says. However, she adds, “lotion may marginally attract more dirt, but not enough to make a huge difference as far as odor.”
While the cultural norm in the U.S. is to shower at least once a day, typically in the morning, showering habits are actually more tied to culture than many would suspect. “There is some evidence to suggest that different ethnicities produce different levels of sebum,” the dermatologist says. “Some people shower every night because that was what their family did,” she says.
The Summer Stick
For many Americans, there is a mental component to a morning shower: “That jolt of water wakes you up. It also makes many people feel fresh for the coming day,” says Dr. Ogunleye, herself a morning washer. But because mornings can be so rushed, many forgo the sunrise rinse and instead wash at night. “If you like your sheets clean or work in a dirty or germ-filled job, that makes sense,” she says.
People with eczema or other skin conditions should take fewer showers, and use lukewarm, not hot, water to keep some of the sebum intact, she says. As long as your bedroom is cool and you’re not sweating all night long, showering in the evening can give a nice coda to a long, hot day, with the added bonus of removing all that icky stick.
She only recommends people shower twice a day if they participate in activities like swimming in bacteria-laden lakes, salty oceans or drying pools, or working out. If you wear open-toed shoes and stomp through city grime, evening showers are useful—though for morning shower-takers, just washing the feet will suffice. “Do most people need to take a second shower?” Dr. Ogunleye asks. “Probably no. Need is a strong term.”
Prepare to Beat the Heat
Some studies have suggested that taking hot baths or showers in advance of a hot day might prep the body for the coming heat wave, but Dr. Ogunleye hasn’t seen strong enough evidence to advise this. “When air hits your skin when you step out of the shower, it’s like sweating, which decreases your body’s temperature,” she says. “As that water evaporates, you will feel cooler, but that feeling lasts minutes, not hours,” she says.
When to shower is ultimately a question of preference. But in the summer, you might sleep more soundly with clean skin. “Kids usually shower at night, when they are sweaty and filthy after a long day, and that makes total sense,” Dr. Ogunleye says.