With so much conflicting information out there, it can be hard to find out what’s true – especially when it comes to trending health and wellness topics, like cold therapy.
Cold therapy has been around for centuries1 to treat injuries and muscle soreness, but it has gained mainstream popularity in recent years, largely because of an overall trend toward healthy living and social media helping topics reach a larger audience. On social media, in particular, people claim just about everything about cold therapy – it helps with energy, mood, and of course, sleep. But does it really provide these benefits, and is there scientific data to back up these claims?
Today we’ll be looking at the science behind cold therapy, including what it is, how it works, and how it impacts sleep.
What is Cold Therapy?
Cold therapy2 is a broad term used to describe treating various ailments with cold. There are cold water therapies, like ice baths, cold plunges, and cold showers, in which you’ll either submerge yourself in the water from the neck down (as with cold plunges and ice baths), or you’ll stand in cold water for several minutes (a cold shower).
Then, there are cold therapies that do not involve submerging yourself or standing in cold water. For example, simply putting an ice pack on an injury is considered cold therapy, as is using a cold spray to numb a localized area.2
Cold Therapy vs. Cryotherapy
Cold therapy is also broadly called “cryotherapy3,” because “cryo” means “icy cold,” or “frost,” stemming from the Greek word “krýos.” So “cryotherapy,” literally translates to “cold therapy.”
However, when people use the word cryotherapy now, they can mean one of three things:
- Cryotherapy: the general word for “cold therapy,” which encompasses all forms of cold therapy (ice baths, cold plunges, cold packs, cold showers, etc.)
- Cryotherapy: the use of extreme cold to freeze and remove abnormal tissues4 like warts or skin tags.
- Cryotherapy: exposing the entire body5 to very low temperatures, either in a small room or a special enclosure. This is also called “whole-body cryotherapy.”
For this article, though, we’ll be using the words “cold therapy” to refer to all types of cold therapies, and we’ll use “cryotherapy” to specifically talk about “whole-body cryotherapy.” Also, when we say “cold water therapy,” we’ll be talking about therapies in which your body is actually in the water, like cold plunges, ice baths, and cold showers.
Cold water therapies differ from whole-body cryotherapy in that with cold water therapy, you’re submerged in water that is somewhere below 60 degrees6 for anywhere between one and 15 minutes. In cryotherapy, your body is exposed to much colder vapors – sometimes as low as -200 or -300 degrees Fahrenheit – for only two to four minutes.5
What is a Cold Therapy Machine?
A cold therapy machine can be a couple of different things. First, it could be a cold plunge tub7, which is a tub that circulates, filters, and cools water to your desired temperature using a built-in cooling mechanism.
Second, it could be a device that is smaller and portable, and it looks a bit like a cooler with a hose attached to it. At the end of this “hose” is a large pad that you can use to place or wrap around an injured area on your body. This machine8 circulates water through the ice reservoir, down the hose, and into the wrap, which both compresses your injured area and cools it. You can think of this cold therapy machine as a more technologically advanced ice pack, used to reduce swelling and speed up recovery.
Is Cold Therapy Beneficial for Sleep?
There are a lot of stories about how cold therapy can improve sleep, but what does the research say? As it turns out, cold therapy can be very beneficial to sleep, depending on what type of cold therapy you’re doing and when you’re doing it.
A little over 10 years ago, a study came out9 showing the benefits of applying cold to a certain part of the head to reduce insomnia. In this revolutionary study, sleepers with chronic insomnia were asked to wear a special cap on their heads at night that would cool the prefrontal cortex. This cooling would decrease the hyperarousal that insomniacs face when trying to go to sleep. Ultimately, the cooling cap reduced their brain activity and lulled them to sleep at a 75 percent success rate.9
Studies have come out in the years since, showing that cold therapy can help with sleep if applied to other areas aside from the head. For example, a 2018 study10 showed that applying cold to the “lateral neck area,” reduced stress levels.
This may be because the vagus nerve is located in this area11 and runs from your brain to your large intestine. The vagus nerve is an important part of the parasympathetic nervous system, which is your body’s system for calming down, or “resting and digesting.”11
It seems that exposing the vagus nerve to ice12 decreases the hyperarousal that people with anxiety and insomnia experience. However, studies only show that exposing the vagus nerve, specifically, has this calming effect. It does not seem to be the same when exposing just the arms or legs to cold water or ice.12
To do this at home, you’d simply place an ice pack or ice therapy machine pad on your chest or neck before bedtime.12
It seems that doing cold water therapy can also help improve sleep13, likely because when submerged in the water, the vagus nerve will also be submerged. Remember, though, it is not necessary to immerse your entire body in cold water to get the relaxing benefits; it is most important that you are stimulating the vagus nerve, which runs from your brain down to your intestines. So, if plunging your body into cold water is not your idea of a fun time, you can simply use an ice pack or ice therapy machine pad on your chest or neck to calm your nervous system.12
Aside from activating the vagus nerve, cold therapy may improve sleep in people with chronic pain, an injury, or certain sleep disorders. For example, cold therapy has been proven to reduce physical pain14 by reducing inflammation and swelling in the area and reducing nerve activity so you’ll be able to perceive less pain. If you aren’t sleeping because of pain in your body, cold therapy could be a good option for you.
Other Cold Therapy Benefits
Cold plunges, cold showers, ice baths, ice packs, full-body cryotherapy, and cold therapy machines all have similar benefits, even though they are done differently. While more research is needed on cold therapy in general, according to UCLA Health, cold therapy can2:
- Bolster your immune system
- Decrease depression and anxiety
- Improve circulation
- Increase your metabolism
- Reduce inflammation and reduce muscle soreness
- Relieve localized pain
Tips for Cold Therapy Before Bed
When using an ice pack or cold therapy machine for sleep, you can place these on your neck or chest just before going to bed to calm down your nervous system.12 However, when using a cold plunge, ice bath, or even cold shower, you’ll want to do this much earlier in the day, since cold water therapy seems to create more energy temporarily16, even though it may lead to better sleep later on.
Who Shouldn’t Do Cold Therapy?
Resting an ice pack on your chest or neck should be safe for just about everyone, but certain people should avoid cold water therapy — or submerging themselves into water below 60 degrees. They include:
- People with heart disease17
- People with any sort of cardiac history18
- People with Raynaud’s syndrome17
- People with high blood pressure17
- People with low blood pressure18
- People with any sort of peripheral vascular disease17
- People who are diabetic and have vascular issues17
- Anyone using Beta blockers18
- People with a low resting heart rate18
It’s also a good idea for those who are pregnant or have other health concerns to check with their doctor before starting any type of cold therapy treatment.
Other Tips for Better Sleep
Sleep hygiene refers to the daytime and nighttime habits that impact your sleep. A lot of us are unaware of our sleep hygiene habits, but gaining control over this can be a huge step toward getting better sleep. The following are some of our favorite sleep hygiene tips that can also help you rest easier.
- Make your room like a cave. Your bedroom should be cool (between 60 and 67 degrees), dark, and completely quiet. If you live in a noisy environment, you might invest in a white noise machine to drown out bothersome noises. In addition, you can make sure your bedroom is clean, free of clutter, and doesn’t otherwise stress you out before getting into bed.
- Develop a calming bedtime ritual. A bedtime ritual is something you’ll do each night before bed that signals your brain and body it’s time for sleep. Some good ideas to include in your bedtime ritual are: reading a calming book, journaling, meditating, drinking herbal tea, or taking a warm bath. Interestingly, taking a warm bath an hour or two before bed actually cools down your core body temperature19, which is good for sleep.
- Activate your vagus nerve in other ways. According to the Cleveland Clinic, you can activate your vagus nerve in other ways aside from cold therapy. Examples of this include calm and deep breaths, exercising earlier in the day, getting a massage, and listening to music.13 Better still, listen to calming music and hum or sing along, which activates the vagus nerve from two directions.13
- Avoid naps. There are several different types of naps, but we recommend avoiding naps that are any longer than 30 minutes or past 3:00 p.m. if you’re having trouble sleeping. Longer naps or naps later in the day can make it harder to get a good night’s sleep.
- Keep a consistent sleep schedule. Go to bed and wake up at the same time each day, including weekends. This will help keep your circadian rhythm in check.
- Avoid certain foods and drinks. Alcohol, caffeine, and sugar should all be avoided, especially at night close to bedtime. You should also avoid eating a heavy meal just before bed.
- Have a light snack before bed. While you don’t want to go to sleep too full, you also don’t want to go to bed hungry. Reach for foods beneficial to sleep, such as tart cherries, kiwi, and nuts.
- Avoid screens one hour before bed. Screen devices like cell phones, tablets, computers, and television sets all emit blue light, which hinders melatonin production20. Since melatonin is an important hormone for facilitating sleep, you should try to avoid screens for one hour before bed.
- Try supplements. Magnesium supplements and melatonin supplements are both considered popular sleep aids. We advise starting with small doses and most importantly, checking with your doctor before taking any.
- Invest in a supportive and comfortable mattress. If you’re currently sleeping on a bed that leaves you feeling unrested or achy in the morning, or if your mattress is more than 10 years old, it’s probably time to get a new mattress.
FAQs About Cold Therapy
Should you take an ice bath before bed?
Taking an ice bath just before bedtime is not recommended since ice baths can cause an initial surge of energy.16 Instead, try taking your ice bath earlier in the day. This may give you more energy during the day and better sleep later that night.13
Is it better to be hot or cold when sleeping?
The body’s core temperature naturally drops21 in preparation for sleep, so it is better to be cold when sleeping. A hot room may disturb your circadian rhythm and won’t encourage melatonin production in the same way a cold room will. While it may seem counterintuitive, taking a warm bath or shower one to two hours b
What are examples of cold therapy?
Some of the most common types of cold therapy include ice baths, cold plunges, cold showers, whole-body cryotherapy, ice pack therapy, and cold spray therapy.2
Natalie is a content writer for Sleep Advisor with a deep passion for all things health and a fascination with the mysterious activity that is sleep. Outside of writing about sleep, she is a bestselling author, improviser, and creative writing teacher based out of Austin.
- Allan, Robert., Malone, James., et al. “Cold for centuries: a brief history of cryotherapies to improve health, injury and post-exercise recovery”. National Library of Medicine. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9012715/. 2022.
- “6 cold shower benefits to consider”. UCLA Health. https://www.uclahealth.org/news/6-cold-shower-benefits-consider. 2023.
- “Cryo-”. Dictionary.com. Webpage accessed October 5, 2023. https://www.dictionary.com/browse/cryo-.
- “Cryotherapy”. Cleveland Clinic. Last modified May 29, 2020. https://my.clevelandclinic.org/health/treatments/21099-cryotherapy.
- “Is whole-body cryotherapy effective and safe?”. Harvard Health Publishing. https://www.health.harvard.edu/staying-healthy/is-whole-body-cryotherapy-effective-and-safe. 2018.
- Machado, Aryane F., Ferreira, Paulo H., et al. “Can Water Temperature and Immersion Time Influence the Effect of Cold Water Immersion on Muscle Soreness? A Systematic Review and Meta-Analysis”. Springer Link. https://link.springer.com/article/10.1007/s40279-015-0431-7. 2016.
- Hounsell, Connor. “Ice Bath vs. Cold Plunge”. Comfort Home Recovery. https://comforthomerecovery.com/blogs/news/ice-bath-vs-cold-plunge. 2023.
- “Pros and Cons Of Using A Cold Therapy Machine”. Campbell County Health. https://www.cchwyo.org/news/2022/july/pros-and-cons-of-using-a-cold-therapy-machine/. 2022.
- Kloc, Joe. “Putting Insomnia on Ice”. Scientific American. https://www.scientificamerican.com/article/putting-insomnia-on-ice/. 2011.
- Jungmann PhD, Manuela., Vencatachellum, Shervin., et al. “Effects of Cold Stimulation on Cardiac-Vagal Activation in Healthy Participants: Randomized Controlled Trial”. National Library of Medicine. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6334714/. 2018.
- “Vagus Nerve”. Cleveland Clinic. Last modified January 11, 2022. https://my.clevelandclinic.org/health/body/22279-vagus-nerve.
- Melani, Debra. “Does TikTok-Fueled Vagus Nerve Icing Offer Calming Relief?”. University of Colorado. https://news.cuanschutz.edu/news-stories/does-tiktok-fueled-vagus-nerve-icing-offer-calming-relief. 2022.
- “5 Ways To Stimulate Your Vagus Nerve”. Cleveland Clinic. https://health.clevelandclinic.org/vagus-nerve-stimulation/. 2022.
- “Cryotherapy Cold Therapy for Pain Management”. Johns Hopkins Medicine. Webpage accessed October 5, 2023. https://www.hopkinsmedicine.org/health/treatment-tests-and-therapies/cryotherapy-cold-therapy-for-pain-management.
- Wafa, Douzi., Claire, De Bisschop., Benoit, Dugué. “Regular short exposures to cold environment as an adjunct therapy for patients with sleep apnea syndrome (SAS)”. ScienceDirect. https://www.sciencedirect.com/science/article/abs/pii/S0306987722000354. 2022.
- Tanner, Lindsey. “Ice baths are hot on social media. Here’s how they affect your body”. PBS News Hour. https://www.pbs.org/newshour/health/ice-baths-are-hot-on-social-media-heres-how-they-affect-your-body. 2023.
- “Cold plunging: Do the benefits outweigh the risks?”. OSF Healthcare. https://newsroom.osfhealthcare.org/cold-plunging-do-the-benefits-outweigh-the-risks/. 2023.
- Williamson, Laura. “You’re not a polar bear: The plunge into cold water comes with risks”. American Heart Association. https://www.heart.org/en/news/2022/12/09/youre-not-a-polar-bear-the-plunge-into-cold-water-comes-with-risks. 2022.
- Neilson, Susie. “A Warm Bedtime Bath Can Help You Cool Down And Sleep Better”. National Library of Medicine. https://www.ncbi.nlm.nih.gov/search/research-news/3495/. 2019.
- “Blue light has a dark side”. Harvard Health. https://www.health.harvard.edu/staying-healthy/blue-light-has-a-dark-side. 2020.
- Harding, Edward C., Franks, Nicholas P., Wisden, William. “The Temperature Dependence of Sleep”. National Library of Medicine. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6491889/. 2019.