(CNN)Ashton Kutcher and Mila Kunis made a splash -- or rather, they don't make splashes too frequently -- when they said they don't bathe themselves or their children too often.
Daily showering, especially in the United States, seems to be ingrained in many people's psyche. You might shower right after you wake up as part of your morning routine, or maybe you like to freshen up and bathe before bed.
How often you should bathe really depends on your daily activities, according to Elaine Larson, senior scholar in residence at the New York Academy of Medicine and professor emerita of epidemiology at Columbia University's Mailman School of Public Health.
"I think people are sort of stuck on, 'How often should I bathe?' or 'How often should I clean my hands?' but it has more to do with what you've done," Larson said. "I think the question is, 'When are the appropriate times to bathe or to wash your hands?' and it's when they get contaminated."
The emergence of modern hygiene practices has been responsible for reductions in many diseases, Larson said. Now, however, most people in developed countries have clean water, soap and clean places to live. This means the main reason for bathing is no longer to prevent disease, but for aesthetic purposes -- to look and smell clean, she said.
For adults who stay inside most of the time, like those of us working from home, Larson said you don't need daily showers. You're in the same environment and not coming in contact with unfamiliar germs that need to be washed away.
This is especially true for older adults, whose skin dries out with frequent washing, leaving them more susceptible to germs, said Larsen, who is also research professor emerita and a special lecturer at the Columbia School of Nursing.
"Generally, you should not be washing every day, because you're actually reducing the normal defense mechanisms the skin has against organisms and infections," Larson said. "In fact, if you clean too often and you get your skin dried out, you're more likely to carry germs and so forth."
This extends to handwashing, too, which she said can dry out your hands and make them more prone to carrying germs if done too often. Though handwashing is essential especially now with the Covid-19 pandemic, washing is mostly necessary when you experience some kind of contamination, like if you cough on your hands or change a baby's diaper.
Also considering the pandemic, we are seeing a lot more people using antibacterial hand sanitizers like Purell, and this may not be great for your skin if you aren't careful, said Dr. Arielle Nagler, assistant professor of dermatology at New York University's Grossman School of Medicine.
"Those products can be really harsh on the skin and can really disrupt the normal skin barrier," she said. "It's fine to do that, but you really need to couple it with moisturizing to help keep your skin healthy."
Especially for people who have dry skin or conditions like eczema, they should avoid long and excessive showers, Nagler said. Those people should take shorter and colder showers, limit soap exposure to areas prone to bad odor, and moisturize immediately after showering.
If you're a big exerciser, she also suggested coordinating bathing around your exercise schedule to avoid taking too many showers.
Bathing recommendations do vary by age, especially for children. Infants should be cleaned with soap once or twice a week, said Dr. Andrew Doyle, a pediatrician at Wellstar Health System in Marietta, Georgia. This excludes the diaper area, of course, which should be cleaned whenever necessary.
If they choose, parents can wash their infants daily with just water, since the skin of newborns is sensitive and should retain its natural oils, he added.
As kids age, bathing frequency should also coincide with "how dirty they get," Doyle said. Once they reach school age around 5 or 6, he referenced the American Academy of Dermatology's recommendations, which say kids need to bathe at least once or twice a week. They should also bathe in the event of activities where they sweat or get dirty, or if they go swimming in a pool, ocean or other body of water.
Once they reach puberty, however, they should take a shower or bath every day, Doyle said. Teens undergo bodily changes during puberty, like producing more oil on the skin and odor in the armpit areas.
Parents should "start those habits for hygiene very early in life with their children and model those for their children and guide them so they can ultimately take control of their health as they grow older," he said.
To instill good bathing practices in kids, he said parents need to make bath time fun and something for kids to look forward to. This can make it easier for children to internalize that habit as something they can control in the future.
Brushing and flossing your teeth
People sometimes don't realize how important oral health is for their overall health, said Dr. Matthew Messina, director of dental oncology and clinic director at the Ohio State University College of Dentistry, who has been a practicing general dentist for 35 years.
"Somehow people have gotten this perception that what happens in the mouth stays in the mouth, kind of like the old Vegas ad, 'What happens in Vegas stays in Vegas,' and we know that's not true," said Messina, who is also a spokesperson for the American Dental Association. "What happens in the mouth doesn't stay in the mouth either, there's interrelations between the body, overall health and oral health."
The mouth is not a sterile environment, he said, and we need to clean it to rid our teeth and gums of bacteria that can come from food that sits in the mouth. If not washed away regularly, bacteria can cause cavities and irritate the gums, causing inflammation. Having inflammation anywhere in the body impacts overall health, so reducing inflammation in the mouth by brushing and flossing is crucial.