How to Take the Perfect Bath, According to Science

·8 min read

Bathing has had quite the journey over the past few millennia, going from a public social activity in Ancient Rome to something done in the privacy of our own homes—first for cleanliness and hygiene, and eventually, as an indulgent way to relax. (There was also a time not too long ago, when, to paraphrase Cosmo Kramer in a 1996 episode of Seinfeld, taking a bath was viewed as sitting in a tepid pool of your own filth.)

But baths have made a strong comeback over the past several years, thanks in part to being marketed as an easy, but indulgent form of self-care (good luck finding a listicle of self-care strategies that doesn't mention bathing). And, unlike many of the other suggested ways to show yourself some love from home, taking a bath is relatively accessible (depending on tub availability, of course): It's something most people can do at home at little or no cost. Better yet, baths are customizable and just for you—meaning you don't have to take into account what someone else wants: You're free to create the bath of your dreams.

But if you're not entirely sure how to take a relaxing bath that's optimal for your body and mood, we're here to help. From finding the ideal bath timing and water temperature to using bath bombs and oils, below are some science-based strategies to improve your experience in the bathtub.

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Find the Right Bath Temperature

Though there isn't a single, “ideal” temperature for bathwater—it comes down to personal preference and the purpose of your time in the tub—for most people, comfortable bath water is around 100 degrees Fahrenheit, Michael Marbach, the marketing director of Kohler Bathing tells Real Simple. And he should know: The company has been in the bathtub business since 1883, when its founder, John Kohler, heated a cast iron horse trough/hog scalder and covered it with enamel—introducing the modern version of the bathtub. Though Marbach’s position involves substantially less farm equipment, it does involve using science and research to create the ideal bathing experience, including tub and bathroom design.

Which brings us back to the temperature of bathwater. Because most standard bathtubs don’t come with a built-in thermometer, temperature is something you’d have to measure on your own (if you really want to be scientific about it). Or, if you’re in the market for a new tub, Marbach says that some of the newer varieties “incorporate digital valves that let you set and control the temperature of the water through an interface panel.”

Here are a few more specific temperature guidelines.

To get squeaky clean:

If your bathtime goal is to get as clean as possible, then Melissa Piliang, MD, a dermatologist with the Cleveland Clinic, does have a number in mind. Though she doesn’t reveal how she arrived at this temperature, in an interview with the Wall Street Journal, she explains that bathing in water 112 degrees F or lower is the optimal temperature for washing away environmental dirt and bacteria.

To reduce the loss of moisture:

Age also is a factor, Dr. Piliang notes. The epidermis is covered with a protective fatty lipid layer that not only keeps dirt and germs out, but also keeps moisture sealed in. The older we get, the longer it takes our skin to replace that lipid layer. “As we age, we have less tolerance for hot water, which may result in dry, itchy, red skin and possibly even eczema,” she tells the Wall Street Journal. Unfortunately, even your favorite moisturizer can’t replenish your skin’s natural oils, Dr. Piliang adds. Keep your bath temp less-than-scalding to protect your skin from irritation, especially if your skin tends to be on the dry, sensitive side.

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To make yourself most comfortable:

Meanwhile, if you’re in the bath for relaxation purposes, the correct water temperature is simply the one that feels right to you. Perhaps you were caught in the rain without an umbrella, and by the time you get home, your clothes are soaked through and you’re so cold that you can feel it in your bones. In that scenario, you might opt for a warmer bath than usual. Or, let’s say you live in a home without air conditioning, and during a heat wave, the only thing that brings you relief is lounging in a lukewarm bath while sipping a cold beer, and reading a book. Again, it all comes down to what you want to get out of any particular bath.

To give your body some balance:

According to Marbach, consider doing a cool rinse after a hot bath (or shower). “Heat penetrates and forces blood flow and circulation,” he explains. “A cool, neutral rinse after a hot bath or shower brings the body to a state of homeostasis—a balanced state.”

To get a good night’s sleep:

Taking a bath in water that’s a neutral temperature—meaning that it’s similar to the temperature of the human body, or around 94-98 degrees F—can be beneficial before bed. “This can provide a relaxing effect on the nervous system of the body,” Marbach says.

What about a room temperature bath?

Another temperature-related part of bathing is the air temperature in the room itself—which Marbach says also comes down to the preference of the bather. “Some bathers like to have a minimal temperature change between the bath water and the air,” he explains, “while others enjoy the rejuvenating contrast between warm bath water and cooler air temps.”

The Perfect Time for the Perfect Bath

How long should you spend in the tub?

Aside from factoring in prune-y fingers, is there anything else we should consider when deciding how long to stay in the tub? Not really, says Marbach, who recommends “soaking for as long as it is comfortable and enjoyable.”

Thanks to Kohler’s own research, however, we do know that nearly 50 percent of bathers enjoy staying in the bath for around 20 minutes. And according to a 2019 study published in the journal Sleep Medicine Reviews that looked at bathing before bedtime, 10 minutes is enough time in the tub to reap the sleep-promoting benefits.

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Is there a best time of day for a soak?

As far as when to bathe, Marbach says Kohler’s data indicates that the evening is the most popular time for a bath, followed by the early morning. “I could see there being some benefit [of a morning bath] for people who have stiff joints—a bath could help loosen joints ahead of the day,” he says. “A quick bath could also increase blood flow and potentially help wake a person up.”

If you’re taking a bath to improve your sleep quality, there is an ideal time for that, according to the same 2019 study. The research found that bathing one to two hours before going to bed is good for our “temperature circadian rhythm” because it helps us fall asleep faster and improves our sleep quality. Scheduling baths around our bedtime improves blood circulation between our body’s core to our hands and feet, which, in turn cools the whole body, preparing it for sleep.

Pro Tips for Using Bath Products

While some prefer their baths au naturel, others like to enhance their soak with products like bath bombs or oils. Before getting into specifics, a word of caution from Marbach: Go ahead with the bath products in standard tubs, but “if you’re bathing in a jetted bath—like a whirlpool or BubbleMassage experience—you need to follow the guidelines of your particular bath carefully, as adding certain elements to your water can cause clogging issues in the system.”

Here, some pointers for making the most of your favorite products.

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How to use bath oils

Adding a few drops of bath oil to your soak not only enhances the experience with an enticing and relaxing aroma, it can also leave you with softer skin. The key here is checking the label to make sure it’s safe to use in the bath. While some people opt to use pure essential oils over products formulated specifically for baths, that’s not always a great idea.

Essential oils like lavender, lemon, and eucalyptus come with benefits. But other oils—like black pepper, clove, and peppermint—can irritate the skin. To make a safe, DIY bath oil, the Tisserand Institute recommends blending five to 20 drops of an essential oil with one tablespoon of a carrier oil (like grapeseed, jojoba, almond, or argan oil). Add the oil right before you’re about to get into the bath to keep it from evaporating.

How to use a bath bomb

Using a bath bomb is pretty straightforward: Fill the tub with water of your desired temperature, drop in the bomb, and marvel as it fizzes and dissolves, dispersing soothing ingredients into your bath. Fun fact: Bath bombs were invented in 1989 by Lush co-founder Mo Constantine, as a more skin-friendly alternative to bubble baths. With such a wide variety of these bubbling balls out there—including recipes for DIY bath bombs—we’ll leave the decisions up to you.

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