Taking a bath can seem like a luxury — something you put off until you have a long weekend or a vacation. But if you have a decent tub, it doesn't have to be that way. In fact, it's one of the few very low-cost ways of relaxing; a box of epsom salts and a bottle of lavender extract will set you back less than $15 and last for quite some time.

If treating yourself to some low-cost stress-relief isn't enough to get you filling your tub, consider some intriguing research from Johannes Naumann at the University of Freiburg in Germany. Naumann found a small but significant amount of relief from depression symptoms in people who took afternoon baths versus people who exercised instead. The study appeared in bioRxrv.

It was a small study — just 45 people — and about half of the participants were taking antidepressant drugs (and those who were taking them continued to). The group was randomly divided into two groups: One group was assigned to exercise twice a week, and the second group was instructed to bathe. Specifically, the bathers were told to go to a local spa (these are common and low-cost community spaces in Germany) to soak for up to 30 minutes in water that was about 104 degrees Fahrenheit. Post-soak, they were told to wrap up in blankets for another 20 minutes. After the first couple weeks of the experiment, some people continued going to the spa while others replicated the bath at home instead.

Tinkering with circadian rhythms

The idea was to raise the body temperature by 2 degrees. Why? Previous research has found that depressed people often have "flatter" circadian rhythms, which are the normal sleep-awake cycles. You can identify these cycles by looking at body temperature. Normally, body temperature rises during the day and falls at night. The cooling off at night encourages the body to release melatonin, which helps us sleep. In depressed people, these natural rhythms can be delayed or less pronounced. Just like getting bright light in the morning seems to make circadian rhythms stronger, so does heating the body during the day.

People in the bathing group in the recent experiment reported that their symptoms were reduced by six points on a typical scale used by mental-health professionals to determine depression severity. The exercisers only lowered theirs by three points. Bathing seemed to work more quickly than the exercise as well. This isn't the first time baths have been found to have a health benefit over exercise.

A hot bath can be stressful on the heart, so if you have pulmonary issues, check with your doctor if this kind of bathing is a good idea. But for the rest of us, a hot bath definitely can't hurt, and is likely to have numerous benefits, from plain-old relaxation of tense muscles to a mental mini-getaway from whatever else is going on in life. Other experiments have shown that before-bed baths can help you sleep by opening up your capillaries and allowing the body to quickly get rid of excess heat quickly. (These results depend on the person sleeping in a cool room.)

If you want to try this at home, keep screens out of the tub — both to reduce stress levels and to keep expensive electronics away from water — and pick up a paperback book. (And if it gets wet, no worries, just leave it out to dry.) No need for fancy bath additions; try epsom salts, essential oils, which are now available even in local pharmacies, olive oil, or just run some shower gel under the bath faucet — it will foam up with bubbles.

Starre Vartan ( @ecochickie ) covers conscious consumption, health and science as she travels the world exploring new cultures and ideas.

How regular baths can help ease depression
Warming the body by 2 degrees with an afternoon bath can help regulate serotonin — and in one study, it was as or more effective than exercise.