Cold plunge tubs have been cropping up in gyms across Singapore as the latest health novelty, while saunas have long been a staple of post-workout relaxation. Both have been used for centuries for purported health benefits. But is there concrete evidence to support temperature therapy? And how can heat and cold be used together effectively?

For centuries, cold plunges and saunas have been utilized for health benefits. Cold plunges help burn fat, improve mood, and boost sleep by activating "cold-shock proteins" in the body which could preserve muscle mass, and reduce cognitive decline and inflammation. Saunas have been linked to heart health, lower cholesterol, reduced inflammation, and better immunity. Biohackers and leaders in the field; Dr. Andrew Huberman and Ben Greenfield are also major proponents of temperature therapy, while Wim Hoff, “The Iceman” has popularized a whole regimen devoted to maximizing health benefits from cold plunges.   

Nordic cultures like the Finnish have long used the "hot sauna, cold water" technique to rejuvenate their body and mind. The science indicates that these effects stem from boosting heart health, managing the stress response, and sleep benefits.

TLDR;

• Cold plunge improves heart health by converting white fat to brown fat, Saunas simulate cardiovascular exercise, and both lower “bad” cholesterol.
• Both therapies improve our ability to respond to stress by releasing neurochemicals, and Saunas reduce stress hormones and signs of inflammation. 
• Temperature therapy generally primes your body for a good night’s rest. 
• All these factors can contribute to greater longevity, and cold plunges and saunas are a synergistic combination that insures against a range of issues.

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Heart health

Cold plunge burns fat and lowers cholesterol

Cold plunges help the heart by promoting fat loss. When exposed to cold water or air for brief periods, the body produces noradrenaline, which breaks down fat cells and releases fatty acids into the bloodstream. This can:

• Fuel your heart and can help lower "bad" LDL cholesterol over time. The risk of fatty plaques blocking your blood vessels, and by extension heart attacks, plummets. 
• Burn calories: In one study, subjects spent 6 hours a day for 10 days in cold environments. After 10 days, the participant's metabolic rates increased by 80%, and their caloric expenditure had risen.
• Studies show that cold plunges stimulate white fat conversion to brown fat, which burns itself.

There are two main types of fat in humans: white fat and brown fat. Brown fat keeps us warm by increasing metabolism when exposed to cold temperatures.

Saunas simulate exercise and reduce mortality

Being in a sauna raises your skin temperature and results in heavy sweating — a short time in the sauna can produce about a pint of sweat.

As your body attempts to keep cool, your heart rate increases and may reach 100 to 150 beats per minute. This opens your blood vessels, increases circulation, and reduces stress levels — similar to the effects of low or moderate exercise.

Furthermore, high blood cholesterol — a waxy substance in your cells, is a major risk factor for heart disease. Lowering your total blood cholesterol by 10% can decrease your risk of heart disease by 30%. Like cold plunges, saunas have a similar effect to moderate-intensity exercise in lowering cholesterol levels. 

In short, regular use of sauna therapy can result in better cardiovascular health. Studies have shown that:

• Regular sauna users experience reduced risk of cardiovascular events like heart attacks and strokes that can lead to death (Laukennen et al.). 
• Increasing the frequency and duration of sauna sessions decreased the long-term risk of cardiovascular disease.
• Sauna reduces all-cause mortality - a general term referring to death from any cause.

Managing the stress response

Cold Plunge trains our stress response

Studies show cold plunges enhance alertness and focus while reducing anxiety.

The initial shock of plunging your body into icy cold water triggers a surge of adrenaline and norepinephrine and dopamine; hormones that boost alertness (sometimes causing temporary agitation). 

• These hormones remain elevated post-plunge, enhancing energy and focus.
• Dopamine (a cousin of adrenaline) is a powerful molecule that enhances mood, sharpens focus, and increases motivation. Even short plunges can lead to a lasting increase in dopamine, boosting your well-being.

Cold stress also activates your prefrontal cortex, the brain area responsible for planning and controlling impulses. This "top-down control" strengthens resilience and grit, allowing you to cope better with everyday stressors.

Saunas lower key stress hormones

Saunas have a longer history of being associated with improved mood, dating back to Roman sweat rooms. The science confirms this – the body's heat response triggers the release of dynorphins and endorphins. Dynorphins initially cause discomfort, but they prime the body for the mood-boosting effects of endorphins, leading to a sense of euphoria after your sauna session.

The heat also offers significant stress management benefits - hormesis, the concept of mild stress triggering positive adaptation, applies here. 

• Regular sauna use can reduce cortisol (stress hormone) levels.
• Activate DNA repair pathways (linked to longevity).
• Increase heat shock proteins that maintain protein structure within cells, crucial for overall health.

Saunas may also be a weapon against inflammation: a major contributor to age-related diseases. Research suggests sauna use might reduce inflammatory proteins, potentially preventing or delaying these conditions and improving overall health. Laukkanen et al. goes further to specify that sauna bathing is highly related to a lower prevalence of dementia and Alzheimer's disease.

Promoting sleep

Cold plunge increases slow-wave sleep

Whole-body immersion in cold water is a natural sleep aid. A 2018 "Nature Scientific Reports" study investigated its effects on sleep quality. Participants who took cold plunges fell asleep significantly faster and reported better sleep quality compared to a control group.

• They experienced increases in slow-wave sleep, the deepest sleep stage crucial for memory, repair, and hormone regulation.
• These benefits likely stem from activating the parasympathetic nervous system - the stress relief mechanism.
• This system increases melatonin (a hormone that helps you sleep well) while decreasing cortisol (a stress hormone).

Saunas prime you for a good night's rest

A 2017 study suggests regular sauna use substantially improved subjective sleep quality. Here's how saunas are proposed to promote better sleep:

• Mimicking Sleep Cycle: The initial heat raises body temperature, followed by a natural drop upon exiting, mimicking the body's natural sleep-wake cycle, potentially signaling it to prepare for sleep.
• Stress Reduction: Saunas also reduce stress hormones like cortisol, promoting relaxation for better sleep.

By incorporating these practices strategically, you can harness the power of both heat and cold to achieve a deeper, more restful sleep - ultimately contributing to a longer, healthier life.

But does hot and cold therapy promote longevity?

While human trials remain limited, initial research on cold plunges using mice models presents intriguing possibilities. A study demonstrated a significant lifespan increase in mice (up to a 20% increase) with a slight decrease in core body temperature. Here at Mito, where extending the human health span is a core focus, such findings warrant further investigation.

Saunas boasts a wealth of human research directly linking them to longevity. A longitudinal Finnish study followed men for over two decades, revealing a 40% lower risk of premature death for those who used saunas frequently compared to infrequent users. Similarly, a comprehensive review of existing research identified a clear association between regular sauna bathing and a reduced risk of cardiovascular events, a major contributor to shortened lifespan. These robust findings solidify saunas as a powerful tool in the fight for extended longevity.

Tips for your next cold plunge/sauna session

Cold plunge

Experts recommend engaging in cold plunges for 11 minutes per week to boost benefits. The temperature varies from person to person, as each individual's cold tolerance is unique (it may not be very high here in Singapore!). 

Aim for 2-3 cold plunges per week, ideally separated by at least a few hours for optimal recovery. It is vital to split the 11 minute weekly threshold up into several separate sessions - in order to optimize cold shock and prevent adaptation (which will reduce benefits). 

Whole body immersion leads to a more significant core temperature decrease, and hence stronger effects. But partial immersion may be more accessible at home (in bathtubs), and can yield similar results. 

Generally, find a temperature that borders between discomfort and being able to safely stay in for a few minutes. As you progress, you may increase intensity by reducing water temperature or increasing exposure duration.

Sauna

To gain the health benefits of deliberate heat exposure, employ sauna therapy for a total of one hour per week, but split this time into two to three separate sessions.

The sauna temperature should range from 80 degrees Celsius to 100 degrees Celsius (176 degrees Fahrenheit to 212 degrees Fahrenheit).

Studies have shown that there is no significant difference between steam or dry saunas - any protocol that enables you to reach the target temperature range should work. 

Combining cold and hot therapy

Switching between hot and cold might seem counterintuitive, but using them in conjunction can harness their synergistic effects. 

The contrasting temperatures create a "vascular pump" – saunas dilate your blood vessels while cold plunges constrict them. This may improve overall circulation and potentially benefit your cardiovascular health.

There's also a metabolic boost at play. Cold plunges stimulate the creation of brown fat, which burns calories to generate heat. Saunas, on the other hand, might help burn existing brown fat. To optimize these metabolic effects, experts recommend ending with cold therapy.

Based on the Søeberg Principle from cold researcher Dr. Susanna Søeberg, forcing your body to reheat on its own stimulates shivering, and further activation of brown fat thermogenesis (fat burning). To put this to practice, finish your temperature therapy sessions with a cold plunge.

Practically, here are some guidelines for structuring your hot/cold routine: 

• Sauna sessions of 12-15 minutes
• Followed by a cold plunge session of up to 3 minutes
• Repeat the cycle 2-3 times depending on your tolerance levels
• We recommend finishing with cold therapy to prevent potential inflammation
• Repeat this routine 2-3 times a week

But stay safe!

Ease into it: Start with warmer temperatures and shorter durations, just like you would with a new exercise routine. Find what works best for you while prioritizing safety.

Stay Hydrated: Drink plenty of water before, during, and after your sauna session to avoid dehydration from sweating.

Sauna Time Limits: Limit your sessions to 20 minutes, with beginners starting even shorter (5-10 minutes) and gradually increasing the duration.

Skip the Alcohol: Avoid alcohol before or during temperature therapy, as it can worsen dehydration.

Consult Your Doctor: If you have any pre-existing health conditions (such as diabetes or heart issues), talk to your doctor before trying sauna or cold plunge therapy. People have varying tolerances to heat and cold, so listen to your body and adjust the experience accordingly.

In conclusion

Both cold plunge and sauna therapy have been conclusively proven to provide health benefits, whether implemented together or independently. Through augmenting heart health, dampening the stress response, and enabling improved sleep quality, both forms of temperature therapy have wide-ranging ramifications for expanding longevity.

Before starting any therapeutic routine, it is always good practice to establish a baseline recording of your biomarkers. Down the line, this can help you assess the extent to which cold plunge and sauna routines improve various aspects of your health and extend your longevity. It may also reveal any latent gaps in your health that temperature therapy or other protocols can bridge.

Our blood test package covers many of the key areas covered in this blog; from ApoB and hsCRP for heart health, homocysteine and cortisol; which has been linked with stress, and 64 other biomarkers. Sign up for our flagship package today to take control of your health and future.

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