The latest trend in health and fitness is plunging your body into frigid water — preferably after detoxifying in a hot sauna. Cold-water immersion, or CWI, involves getting into water that is between 55 and 45 degrees Fahrenheit, says Verywell Fit. As unpleasant as that may sound, many people swear by the health benefits of CWI.

Cryotherapy has been used since 3500 B.C. by the ancient Greeks who believed cold water therapy was essential for relaxation and socialization purposes. You can try CWI by jumping into a cool natural body of water, filling your bathtub with ice water, or buying a special tank that’s made for the purpose.

According to experts, the health benefits of a cold plunge include:

• Reduces stress. Cold water activates the vagus nerve, the longest nerve in the body, which in turn affects the parasympathetic system. This helps reduce stress.

• Calms inflammation. Exposing your body to cold temperatures causes blood vessels to constrict, reducing blood flow. This helps reduce inflammation and muscle soreness.

• Improves mood. CWI helps release certain hormones including the stress hormones noradrenaline and cortisol, as well as dopamine, the ‘feel good hormone.” So, your mental health benefits.

• Helps recovery from intense exercise. Post-fitness cold water plunging helps athletes recover by slowing down metabolism and helping muscles recover from the tiny microtears that happen during exercise, says Jamie Bacharach, a Jerusalem-based expert in acupuncture and an expert in both Chinese and Western healing therapies.

• Benefits mental health. When the feel-good hormones are released into the body during CWI, people enjoy more intense feelings of happiness and satisfaction, according to studies. These hormones also bring mental clarity and help motivate people to perform more complex tasks.

• Boosts immune response. “White blood cells found in your body known as leukocytes, which play a large role in fighting off sickness and disease in the immune system, are stimulated by a cold plunge as part of your body’s fight or flight response,” says Bacharach. Cold temperatures also affect your lymphatic system, forcing fluid through the lymph nodes to detoxify the body.

• Potentially delays dementia. Researchers at Cambridge University found that swimming in frigid waters increased levels of a “cold shock” protein called RBM3 that has been found to offer protection against the onset of dementia in mice models. The lead researcher of the study, Giovanna Mallucci, said that the next step is proving that the protein can delay the disease in humans and then developing a pharmaceutical method to stimulate its production. According to BBC News, Mallucci says the discovery could also point to new avenues of treatment to keep dementia at bay. The RBM3 protein has been shown that it not only delays dementia in mice models, but also repairs damage to the brain.

Important: Start slowly with CWI, say experts. Listen to your body and stay in the cold water for only 30 seconds the first time around, gradually increasing your length of exposure over a few weeks to five to 10 minutes. Bacharach warns that if you feel any pain or discomfort you should get out of the water. People with cardiovascular diseases, respiratory issues, or circulatory disorders should avoid cold plunging. She also cautions that cold plunging should not be done during pregnancy as it may add stress to the body.

Also, be aware that hypothermia, or low body temperature, can occur if your body temperature drops below 95 degrees Fahrenheit. Hypothermia can lead to cardiac arrest and death. “If you experience any symptoms of hypothermia, such as shivering, confusion of slurred speech, get out of the water and seek medical help,” says Bacharach.