The Science Behind a Cold Plunge

Cold plunges have become exceedingly trendy in recent years, but they’re not a new invention. Researchers have uncovered evidence of people in ancient civilizations taking ice baths for health and rejuvenation as far back as 3500 B.C.

Now, science reveals this chilly practice offers some incredible perks for your health. Read on to discover the health benefits of cold plunge therapy, how to get started and risks to consider.

But first, let’s define what we mean by a cold water plunge.

What is a cold plunge?

As the name implies, cold plunge therapy–also called cold water immersion or cold therapy–involves submerging yourself in ice-cold water, often for at least 30 seconds.

Ideally, ice baths are between 50 and 60 degrees Fahrenheit. This temperature strikes a good balance between effectiveness and safety. Beginners may start at the warmer end of this spectrum and work their way downward as they build a tolerance.

Some of this therapy’s most popular advocates are athletes, who frequently soak in ice baths after competitions to reduce soreness and inflammation. One particularly well-known proponent of the practice is Dutch extreme athlete, Wim Hof, who holds the nickname, “The Iceman.”

Hof has set numerous cold exposure records, including climbing Mount Kilimanjaro in nothing but a pair of shorts.

But you don’t have to be an athlete to enjoy the benefits of cold therapy. Many people use whatever resources they have available to “chill out,” utilizing:

Icy lakes
Freezing-cold oceans
Specialized tubs designed to retain cooler temperatures
Ice-filled bathtubs
Cold showers (although not being fully submerged may provide less profound effects)

Health benefits of cold plunge therapy

The science behind cold plunge therapy has been mounting for decades now, highlighting a number of impressive advantages:

1. Improved focus and mood

Studies suggest cold plunges can sharpen your focus, as well as lift your mood. Cold exposure stimulates the release of adrenaline and endorphins, increasing alertness and positive feelings.

If that weren’t enough, it also triggers a significant rise in dopamine levels, another “feel-good” hormone that boosts motivation and concentration.

According to one study, a dip in 57°F water can boost dopamine levels by 250% and norepinephrine–a hormone that reduces inflammation and pain while supporting healthy mood and attention–by 530%. These effects can last several hours after your plunge.

Participants in the above study also reported substantial improvements in:

Depressive symptoms
Self-esteem
Feelings of vigor

2. Increased energy

The release of norepinephrine, adrenaline, and endorphins also means you’ll experience increased energy levels and better athletic performance.

Cold exposure provides a boost for mitochondria–the energy “powerhouses” of cells–as well. This increase promotes the creation of new mitochondria and improved efficiency of existing ones.

For an even bigger uptick in energy, pair cold therapy with exercise. Cold exposure significantly impacts a protein called PGC-1alpha, which is vital for energy metabolism. And exercise influences a different protein called TFAM, which supports mitochondrial DNA maintenance.

3. Body-mind resilience

Stepping into a freezing body of water is not for the faint of heart. It takes determination and is, therefore, a powerful method to build resilience and adaptability to challenging situations.

While the shock of ice-cold water might seem to trigger a “fight or flight” response initially, repeated cold plunging trains your body to engage its “rest and digest” mode (the parasympathetic nervous system), even in harsh conditions.

Cold water therapy also reduces levels of the stress hormone, cortisol, meaning it could potentially help you deal with unnerving situations on a more even keel. The calming effects of an ice bath can last for up to three hours afterward.

4. Higher-quality sleep

As mentioned previously, cold therapy stimulates the parasympathetic nervous system and reduces cortisol–which can also help you sleep better. In fact, ice baths could increase the amount of deep, slow-wave sleep you get by a whopping 35%.

What’s more, researchers posit that the drop in body temperature during a plunge mirrors the natural decrease in body temperature that happens right before sleep. This means ice baths could support your body’s production of melatonin, another sleep enhancer.

Endorphins also contribute to quality sleep by fostering a more relaxed state of mind.

5. Reduced soreness and pain

According to Dr. Tracy Zaslow of the California hospital, Cedars-Sinai Kerlan-Jobe Institute, “When you’re in cold water, your blood vessels constrict so there’s less blood flow to the area, then there’s less swelling and inflammation leading to less pain.”

Research confirms that cold plunges can reduce inflammation and delayed onset muscle soreness, or muscle pain that appears 1-2 days after vigorous exercise. Ice baths also reduce levels of creatine kinase, a marker of muscle tissue damage.

Study participants have also reported better “perceived recovery,” or a readiness to take part in more physical activity. So, the next time you’re headed for an intense workout, consider planning an ice bath afterward to get back on your feet faster.

6. Stronger immunity

Another surprising benefit of cold water therapy is improved immune function. Immersing yourself in icy water increases the body’s production of immune cells. These include white blood cells and natural killer cells–both critical for combating infections, as well as cancer.

Cold exposure also:

Helps manage chronic inflammation, which if left untreated, can weaken immune defenses
Stimulates lymphatic drainage from muscles, eliminating toxins
Decreases cortisol levels, which, in excess, can suppress the production of immune cells

So if you suffer from frequent infections–or are concerned about your cancer risk–you might want to give ice baths a try.

7. Faster metabolism

Some research suggests cold plunge therapy can speed up your metabolism and promote weight loss. In fact, one study found its participants experienced a 350% increase in metabolic rate after being submerged in 57.2-degree water.

Researchers also noted a rise in participants’ plasma noradrenaline, a chemical that helps break down body fat.

Exposure to cold temperatures appears to boost metabolism through both shivering and non-shivering thermogenesis, as well. Non-shivering thermogenesis involves the use of brown fat, or brown adipose tissue (BAT).

BAT is loaded with mitochondria that burns calories to generate heat without causing shivering throughout the body.

Regular cold plunges support the production and activity of brown fat, potentially increasing its effectiveness at burning fat. So, if you’re trying to lose weight, consider regularly soaking in ice baths until you start shivering to maximize both kinds of thermogenesis.

8. Improved insulin sensitivity

Cold water therapy can also support those with type 2 diabetes or pre-diabetes. In fact, it could improve insulin sensitivity–a critical ability to use glucose more efficiently–by 43% after just 10 days, according to one study. That’s significantly more than exercise alone.

Cold plunging helps by:

Prompting glucose absorption in skeletal muscles, reducing blood sugar levels
Activating BAT through cold exposure, which helps metabolize glucose
Reducing stress, which helps level cortisol and adrenaline levels, supporting metabolic health

Some studies suggest cold plunging can affect your body’s insulin response for up to 48 hours. So if you’re concerned about diabetes, consider plunging at least once every other day.

9. Better heart health

Cold plunges can even boost your cardiovascular health, primarily by:

Improving circulation by initially constricting and then dilating blood vessels
Reducing inflammation, which, if unchecked, can contribute to heart disease
Combating stress
Potentially lowering blood pressure via reduced inflammation and the body’s natural adaptation to cold temperatures
Activating BAT and improving insulin sensitivity, which have been linked to lower risks of heart disease

So consider a cold plunge practice to keep your heart and entire cardiovascular system going strong.

How often should I cold plunge

For general health and well-being, many people experience cold plunging’s benefits through only 2-3 sessions per week. But your ideal frequency will depend on your:

Goals
Cold tolerance
Underlying health conditions

Athletes or those who enjoy intense workouts may benefit more from daily ice baths. Start with 30 seconds a few days per week, paying attention to how you feel, and increasing your frequency and duration as needed.

Who shouldn’t take cold plunges?

It’s important to note that cold plunges may not be suitable for everyone. Talk to your doctor before attempting them if you have been diagnosed with:

High blood pressure
Heart disease
Poor circulation
Cold agglutinin disease
Peripheral neuropathy
Diabetes
Venous stasis

It’s possible that, under medical supervision, those who might typically be advised against cold plunging could still reap its benefits. Talk to your healthcare provider to determine whether this practice is a safe and viable option for you.

Risks of cold therapy

Cold plunges carry some drawbacks that make it unsuitable for some, and still potentially risky for others:

Cardiovascular stress

Sudden exposure to cold water can spike your blood pressure and heart rate initially. If you have a heart condition, make sure to consult your doctor before attempting a plunge.

Hypothermia

Prolonged exposure to ice-cold water could cause hypothermia (dangerously low body temperature)–which, in severe cases, can be life-threatening. To minimize your risk, keep your plunges brief–between 30 seconds and 15 minutes in 50-60-degree water.

Hypothermia can develop quickly, so don’t push it, and avoid large bodies of water that limit your ability to enter and exit quickly.

Hyperventilation

The shock of entering cold water can tighten your airways, potentially causing hyperventilation. Ice baths at home provide lower risks of hyperventilation than natural bodies of water because, if you start struggling to breathe, you can quickly get out.

Drowning

The risk of drowning is mainly associated with natural bodies of water, such as lakes, rivers, or oceans. If you submerge yourself in a partially frozen lake, you could get trapped under the ice. Or, in the ocean, an unusually strong rip current could sweep you out to sea.

So play it safe, and create an ice bath at home if possible. You can find special cold plunge tubs for sale online, or simply fill your bathtub with ice and cold water.

The bottom line

When you look at the science, it’s clear that cold plunge therapy isn’t just about acclimating to cooler temperatures. It’s about harnessing better health and vitality.

Ice baths can provide many health benefits, including sharper focus, better mood, stronger immunity, and a healthier cardiovascular system.
There are a few risks associated with cold plunges, such as cardiovascular stress and hypothermia. Working with your doctor and taking ice baths at home can minimize some of these risks.
Start with short plunges, and gradually increase your frequency and duration to reap maximum benefits but ensure your own safety.
Consult your healthcare provider to determine if cold plunge therapy is appropriate for you if you have any pre-existing health conditions.

Be cautious and know your limitations. But before long, you’ll be a seasoned polar bear ready to tackle both the literal and metaphorical cold.

References:

Health effects of voluntary exposure to cold water – a continuing subject of debate – PMC

Human physiological responses to immersion into water of different temperatures

Does the Wim Hof Method have a beneficial impact on physiological and psychological outcomes in healthy and non-healthy participants? A systematic review | PLOS ONE

Improved mood following a single immersion in cold water – Kelly – 2022 – Lifestyle Medicine – Wiley Online Library

Physiology, Noradrenergic Synapse – StatPearls – NCBI Bookshelf.

Impact of Cold-Water Immersion Compared with Passive Recovery Following a Single Bout of Strenuous Exercise on Athletic Performance in Physically Active Participants

The effects of cold water immersion and active recovery on inflammation and cell stress responses in human skeletal muscle after resistance exercise – PMC.

Post exercise ice water immersion: Is it a form of active recovery? – PMC.

Cold for centuries: a brief history of cryotherapies to improve health, injury and post-exercise recovery

Short-Term Head-Out Whole-Body Cold-Water Immersion Facilitates Positive Affect and Increases Interaction between Large-Scale Brain Networks – PMC