Hot water, cold water, hot water. This simple routine, called “contrast bathing,” is invigorating and restorative.

What it does: “Contrast bathing is a great way to stimulate lymphatic drainage, improve skin health and enhance circulation,” says Andrew Rubman, ND, medical director of Southbury Clinic for Traditional Medicines in Southbury, Connecticut, and a contributing medical editor for Health Insider.

How it works: The exact mechanisms haven’t been proven, but it’s known that blood vessels dilate when your body gets warmer, and constrict when it gets colder, so the hot/cold combo stimulates circulation. The increased circulation is also good for your skin. Plus, that vascular dilation and contraction is believed to stimulate the lymph system, which builds white blood cells and removes infectious microbes—boosting immunity. And studies have shown that exposure to cold water enhances immune function.

How to do it: “During a daily shower,” says Dr. Rubman, “flip the temperature control from normal hot to quite chilly cold for a good minute—and then back to hot for about five minutes.”

Who shouldn’t do it: If you have cardiovascular disease, peripheral artery disease or are pregnant, talk to your doctor first. If you get the go-ahead, start with cool and work your way up to cold.

Contrast bathing and other forms of hot/cold-water therapy can also enhance recovery from sore muscles from exercise…and ease a sore throat. To learn more, see Bottom Line’s Cold Water Therapy for Strength, Energy and Healing and The Secrets of People Who Never Get Sick.