Cold showers are typically an unpleasant occurrence that happens when you run out of hot water. However, some people are now touting the benefits of a cold shower when it comes to sleeping better at night.

In this article, we’ll look at what the research says about how cold showers — and hot showers — affect your body and your ability to sleep.

For hundreds of years, cold bathing has been a way to invigorate the body. Ancient Romans used to progress through several heated rooms before plunging into a cold bath. Today, most people simply turn the dial on their shower to get a cold blast.

There are a lot of reported benefits of cold bathing or showering on the body. These include:

  • enhancing immunity
  • enhancing overall feelings of vitality
  • improving blood circulation

However, there aren’t a lot of definitively researched benefits. We’ve included some below.

May make you feel more awake and alert

Researchers in an older 2002 study found that cold exposure activates the sympathetic nervous system. As a result, the body releases hormones such as norepinephrine and cortisol. Norepinephrine particularly triggers a reaction in the body’s blood vessels designed to redistribute the blood and warm the body.

Cortisol is another consideration. The body releases cortisol levels throughout the day that follow a fairly predictable pattern. Cortisol usually peaks at around 9 a.m. and decreases to its lowest point around midnight. Some studies have connected increased cortisol levels at night with poorer sleep.

Do cold showers help you sleep?

Researchers haven’t looked specifically at whether cold showers can increase cortisol levels and affect sleep.

However, one study on cold exposure found that the body releases cortisol when exposed to the cold, while another found that increased levels of cortisol at night may lead to poor sleep. This could suggest that taking a cold shower before bed may be less beneficial for sleep.

Cold showers may be helpful for those who want to feel more awake or alert during the day.

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May boost your immune system

To test the theory that cold showers boost the immune system, researchers randomized more than 3,000 participants to four trial groups: one group took hot showers only, while three groups took hot showers and included a blast of cold water for 30, 60, or 90 seconds at the end of their shower.

At the study’s conclusion, the researchers measured factors like reported illness and sick days over 30 days. They found that those who included any blast of cold water during their shower had a 29 percent reduction in sick days than those who took hot showers only.

Interestingly, the participants didn’t report that they were sick over fewer days, just that their symptoms weren’t as intense, so they were able to work. The researchers theorized the cold water may have helped reduce the intensity of their perceived symptoms

Soothes sore muscles after exercise

Professional athletes have long used ice baths to soothe sore muscles after a game or race. While cold showers may enhance hormone levels in those who are sedentary and take a cold shower, they can have the opposite effect on those who exercise.

A 2015 study looked at high-intensity cyclists exercising in warm temperatures. The researchers asked a control group to take a cold shower for 1 to 3 minutes. They asked another group to omit the shower.

The researchers found that those who took a cold shower after exercising were able to decrease their heart rate more quickly and felt more comfortable, compared with those who didn’t take a cold shower.

The researchers also measured cortisol levels in both groups, but didn’t find any key differences.

Potential downside: You may incur lingering cold sensations

There aren’t many known downsides to cold showers. In a 2016 study that examined the effects of cold showers, about 13 percent of participants reported a persistent sensation of cold in their body, including their feet and hands. The researchers didn’t note any other side effects.

Fortunately, there are a few more studies on hot showers before bed and sleep. Some of the results are below.

Improves sleep quality

A 2019 systematic review found that taking a warm shower or bath (104 to 108°F, or 40 to 42°C) for at least 10 minutes 1 to 2 hours before bedtime improved the participants’ sleep quality more than those who didn’t take one.

Lowers blood pressure at bedtime

A 2019 study found that soaking in a warm bath for 11 to 15 minutes before going to sleep helped older participants lower their blood pressure before bed. Some participants’ blood pressures dipped as much as 16 mm Hg after a warm bath.

Helps you fall asleep faster

A recent study looked at more than 1,000 older adults with an average age of 72 who took a hot bath before bedtime.

The researchers found that those who took a hot bath before bedtime reported falling asleep quicker than those who didn’t take a hot bath before bed.

Potential downside: It may dry or irritate your skin

Like cold showers, there aren’t a lot of harmful side effects related to hot showers, providing the shower water isn’t too hot and you limit your shower time to around 10 minutes. Otherwise, the water could dry and irritate your skin.

The available research on the effects of hot or cold showers on sleep shows that people have a variety of responses to water temperature. This makes hot or cold showers before bed, and whether they can improve your sleep, seem more like a matter of personal preference.

Generally speaking, there’s more data to support that hot showers help improve sleep. This is likely because warm showers are thought to be relaxing, while cold showers are thought to be stimulating.

However, there aren’t studies that compare hot and cold showers head-to-head, so we’ll let you experiment and determine the best option for you.

Fortunately, you don’t have to rely on showering alone as a way to improve your sleep. Here are some other steps you can take to sleep better at night:

  • Go to bed at the same time every night. This will help keep your body in a routine.
  • Keep your room dark closer to bedtime. Decreases in light can trigger the body’s natural rhythms toward sleep.
  • Avoid doing any activities that can increase your alertness and, as a result, affect your ability to go to sleep. These include drinking caffeine, drinking alcohol, or engaging in vigorous exercise before bed.
  • Make sure your bedroom is cool, but not cold. The ideal room temperature is around 65°F (18.3°C).
  • Maintain a relaxing routine before bed, such as taking a warm bath or shower, meditating, reading, or journaling before bed.
  • Try to keep your bedroom for sleeping only. This means refraining from computer, phone, or television use that could otherwise keep you up later at night.

Showering before bed can be part of your overall better-sleep strategy, but there isn’t a lot of research to support the idea that a cold shower is the way to go.

However, if you find that a blast of cold water before leaving the shower helps you sleep better at night, consider incorporating it as part of your nightly routine.