How a 30-second blast of cold water at the end of a shower may boost immunity

• Cold showers may have benefits for your hair and skin since warm water can strip natural oils away.
• Cold water may also help you feel more alert and help with muscle recovery after a workout.
• But the harsh shock of cold water may put you at greater risk for a heart attack.

The idea of a cold shower can be intimidating, but if you brave the cold, it can offer great health benefits.

Studies show that cold water may stimulate blood flow, boost mood, promote healthier skin and hair, and more.

Note: There have not been large-scale studies on these benefits, but some early research is promising. More and higher-quality research is required to support these claims.

Here are six science-backed benefits of taking cold showers.

1. May boost your immune system

Studies show that when your body is exposed to cold, you produce more white blood cells, the cells your body uses to fight off infections.

This may be partly why cold showers can boost the immune system.

For example, a 2016 study from the Netherlands found that people who added cold showers into their regular routine were statistically less likely to self-report sickness.

The study showed that adding just 30 seconds of cold water - about 50°Fahrenheit - at the end of a warm shower was enough to have an effect.

2. May relieve depression

Cold showers stimulate nerve receptors in your skin, which in turn stimulates activity in your brain and may have an anti-depressive effect, says Michele Green, MD, a dermatologist in private practice.

A 2008 study found that participants who were exposed to cold water experienced relief from symptoms of depression. Moreover, the study stated that the cold water therapy did not have any adverse side effects.

However, the study also makes a point to note that "more rigorous studies would be needed to test the validity of the hypothesis" that cold water can relieve depression.

Moreover, don't consider cold water showers a replacement for an anti-depressant medication you may be taking.

3. May make you more alert

When cold water hits your body, it causes a minor shock and stimulates your sympathetic nervous system.

Your sympathetic nervous system controls the automatic functions of your body like your heart rate and digestion. It also helps you respond quickly to stress, so it can trigger functions like increasing heart rate, sweating, and increased alertness

4. May keep your hair healthy

"Cold water for the hair is better than hot water," says Debra Jaliman, MD, a dermatologist and professor at Mt. Sinai.

This is because hot water may be more likely to strip away the natural oils in your hair that keep it shiny and healthy.

Showering with cold water increases shine and helps smooth the outer layer of hair strands called the cuticle, so that your hair looks less frizzy, Jaliman says.

5. May help relieve dry skin

If you're looking to prevent chapped skin - especially when it's dry and cold out - you may want to lower the water temperature of your shower. "Cold or cool showers do not dry out your skin as hot water showers do," Jaliman says.

Similar to how cold water affects hair, a cold shower is less likely to dry your skin out by stripping away the natural oils that keep your skin hydrated, says Jaliman.

If you already have dry skin, hot water may exacerbate it. "Hot baths can cause inflammation, redness and itching," Jaliman says. Cold water decreases inflammation and can help reduce swelling and itching.

6. May help with recovery after a workout

After a difficult workout, your muscles are left inflamed and fatigued. Cold water can help with recovery.

A 2018 analysis of 99 studies found that exposure to cold water was effective at reducing muscle soreness and fatigue, though it wasn't as effective as massage therapy.

The athletes in these studies used cold water immersion, which involves getting into a cold water bath or pool, often around 50 to 60°F. The athletes reported feeling the benefits as long as four days after treatment.

Risks of cold showers

People with heart disease should be careful when trying cold showers.

The harsh shock to your system could potentially put you at greater risk for heart attack. If you have any heart issues, it's best to talk to your doctor before starting cold showers.

It's also possible to overdo the cold. "If the water temperature is too cold, below 10°C, and you take a long shower, you can get hypothermia. I recommend cold showers between 10°C/50°F and 16°C/60°F," Green says.

Insider's takeaway

Cold showers can offer many important benefits, including muscle recovery, moisturized skin and hair, and increased blood circulation. But exposure to cold can also carry risks, so check with your doctor before trying it, especially if you have certain health issues like heart disease.