How I Improved My Chronically Low HRV – Strategy to Increase HRV While Sleeping

Previously, I wrote how the continuous HRV monitor by Lief Therapeutics has been a game changer for me to improve my HRV (read my previous articles here, here and here). But what are these game-changing actions that the continuous HRV monitoring helped me to take?

Though I find very helpful the vibration-based biofeedback, this is not why I consider the device a game-changer. Don’t get me wrong – deep breathing is one of the best ways to have an immediate positive impact on the HRV, and a frequent deep breathing will likely increase your average daytime HRV by making the score higher while you are making a conscious effort. Nevertheless, to my frustration, breathing exercises did not make better my nighttime HRV nor daytime baseline HRV when I’m not actively trying to improve my HRV.

Many other strategies resulted in only temporary HRV improvements without changing my baseline HRV. They include: Apollo Neuro, Neuvana, sniffing grapefruit essential oil (a study showed that sniffing certain fragrance such as grapefruit essential oil improves HRV), and vagus nerve exercises, like in the book “Accessing the Healing Power of Vagus Nerve”.

Cold exposure: In my previous post, I reported an incredible effect of a whole-body cold exposure to increase HRV. While I still consider it a very potent way to improve HRV instantly and highly recommend it as a great temporary HRV hack, I have not seen a strong evidence for myself that the improvement gets converted into a permanent increase of the baseline HRV.

Supplements such as a high dose of omega 3 and Parasym Plus (a proprietary mixture that targets at the parasympathetic nervous system) had no impact on my HRV, neither baseline nor temporary. (Omega 3: I have been taking it for years and merely increased the dose from 3 g of DHA & EPA daily to 4 g to see if it improves my HRV, which it didn’t. If you are not taking DHA/EPA at all, the effect might differ. )

Additionally, I tried a nasal oxytocin spray (24 IU) twice daily but experienced no HRV improvement whatsoever.

What puzzled me the most was that my HRV seemed to have very little to do with how I subjectively felt about my stress level. How, at the end of a very easy stress-free day, could I routinely see my HRV a low teen? Also, why was my HRV dropping precipitously whenever I was standing? In both situations, I was not experiencing any stimulus that would particularly stimulate my sympathetic nervous system. After countless days of staring at my Lief, I got an idea; Could it be a suboptimal cardiovascular system causing the low HRV, not an overactive sympathetic nervous system? Because my heart rate was elevated in both above situations, as if my heart had to work extra hard to keep me going late in a day or while on a standing position, it seemed worth exploring above hypothesis. So, I decided to reintroduce vigorous endurance trainings, which used to be a big part of my training regime bur during the recent years had become increasing less.

Picture to the left, HRV in late afternoon, on the right HRV while standing

Over 10 years ago, I injured my legs and had to go on crutches for a few months. Afterwards, I stopped running, an activity I previously used to do 3-4 times a week. As I continued lifting weights and walking regularly, I somehow assumed that it shouldn’t be a big deal to drop running. This significantly reduced the amount of endurance exercise that would get me out of breath, and especially during the past few years, when I no longer participated in gym classes like spinning, the amount of peak-zone endurance trainings had become almost non-existent.

In a hindsight, this must have significantly affected not only my cardiovascular fitness level but also HRV; After re-introducing running into my daily regime, my resting heart rate started to drop in a matter of just a few days. I was even more pleased that, as my RHR dropped, my HRV started to go up and UP! And both kept improving dramatically. After three months of reintroducing vigorous endurance exercises 4-6 times / week, my HR while sleeping dropped from 66 to 59 bpm, and my average nighttime HRV from an upper teen to lower 30s.

To the left: nighttime RHR, previously in a high 60s (sometimes even a low 70s) to low 60s/high 50s in just three months. To the right: Nighttime average HRV, increased from a mid/upper teen into a low 30s

Previously, my HRV at night could routinely drop to a low teen, and I was giving myself a high-five on occasions the number was in low 20s. Now, a mid-20 nighttime HRV may make me a sigh with a disappointment, as this has become my new lowest HRV range. After a restful night, my average nighttime HRV can easily be in the 30s now.

There are multiple studies that show the positive impacts of endurance exercises on vagus nerve tone i.e. HRV [1], [2] [3]. But initially, I was solely focused on finding the reasons for my chronically low HRV in stress and overactivated sympathetic nervous system, overlooking exercise.

Obviously, if your cardiovascular fitness is already optimized, adding more cardio-conditioning exercise is not likely going to improve your HRV. But if you find yourself in a similar situation like mine, the strategy might be worth considering. Please don’t start a high-impact exercise without speaking to your doctor first. Other than the low HRV, I consider myself healthy and also prior to resuming running, monitored my blood pressure and ECG daily with Withing Blood Pressure Cuff to ensure that I had no issue with half-an-hour of vigorous exercise.

Through the experience, I was once again reminded of the importance of self quantification, whether it is the effects of diet through regular blood marker testing or our estimated biological aging through test like GlycanAge. A continuous HRV monitoring can provide eye-opening insights that makes possible a personalized plan for optimizing your HRV. By making me realize how detrimental it was for me not to practice any vigorous endurance exercises, Lief truly made a lasting impact on my health even beyond HRV.

Get a nice discount with the discount coupon EEVA at checkout at Lief! The code is valid both for device purchase & rental.



Health Wearable Review: Lief Continuous HRV Monitor by Lief Therapeutics

From the very first day I had Lief on, it changed my life completely providing insights previously unavailable. This may sound a little dramatic, but for me, who had no clue for why my HRV is routinely so lousy, continuous HRV data finally pinpointed which types of activities and/or life choices are hurting my HRV score.

But how is it like to use Lief? It comes with a wearable ECG hardware and an app that shows your HRV data. Are they easy to use? Which features do the app offer? Do I wish for any improvements? This article covers those and many other questions. If you are also interested in my personal HRV discoveries that I found out using Lief, you may find interesting these articles; “Is Standing Workstation Hurting HRV?”, “Try This One Thing to Improve Your HRV Instantly”.   

The Lief Wearable

Lief is a clinical-level ECG wearable, attached to the chest area with two adhesive electrode patches. I can usually reuse the same patches well over 3 weeks while wearing them every day. If the adhesives are getting weaker, you can wipe them with a wet paper/towel to make them sticky again.

Lief is flexible and adjusts to the body’s dynamic movements. As such, it’s super comfortable, and I often forget that I’m having it on me! It can be worn during sleep, too, and if you choose this option, you can turn off the biofeedback vibration (more about Lief’s biofeedback feature later) while you are asleep. I personally wear Lief during my aware time, because I’m primarily interested in discovering and implementing actionable insights to improve my HRV.

Lief wearable

ECG vs. Optical Sensors

Let us take a closer look at sensors, one of the key components while considering an HRV (or many other types of) wearable. The choice of sensors is important, because it affects the wearable’s accuracy greatly. When it comes to an accurate heart’s signal measurement, a direct measurement of the heart’s electronical signals with ECG is the clinical golden standard – that’s why you’ll be hooked to an ECG machine, when you go through a heart checkup at the doctor’s office. For a wearable, though, many manufacturers choose optical sensors instead, for a cost or other reason.

Optical sensors flash LEDs through the skin and detect blood flow. The resulting reflection of the light is converted into a heart rate via the wearable’s algorithm, making it more prone to inaccuracy. Moreover, there are two types of LEDs used for optical sensors: red and green. Optical sensors that emit green light can result in even less accurate data especially on a darker skin, because melanin, the skin’s color pigment, is an excellent absorber of the green light.    

In my interview with Rohan, founder & CEO of Lief Therapeutics, he shares fascinating background for why ECG sensors were the best and most natural choice for Lief.

In this Kickstarter page, you can see Lief wearable’s technical spec with a picture of the ECG sensors.

The Lief App

Live HRV tracking

The Lief app shows three variables; heart, HRV and HRV zone in a colored bar form. The HR and HRV are live data i.e. you will be seeing your HR and HRV of this moment. The HRV zone gets updated every 5 minutes, and the color and length of the bar visualize the average zone you were in. Lief customizes the zoned according to your previous data. For example, Restore Zone (the “best HRV zone”) for me at this moment is any HRV values over 19, whereas the same values for other users can be within the Alert or even Tense Zone (the lowest zone).


You can initiate Lief’s biofeedback vibration in three different ways; by choosing the Train option in the app’s menu, by tapping the wearable and having a very low HRV in the Tense Zone that will automatically trigger the vibration. On the app, you will see prompts to exhale and inhale. Lief customizes the durations of the exhalation and inhalation basing it on your breathing data. The vibration is noise-free and discrete – only you will know that it’s on.


Lief offers basic statistical insights including average HRV over a given period. Under app’s menu “Progress”, you can display the average HRV, HRV range, Downtime Dosing, and Wear Time during a week, month or a customized period. To move to the previous/next period, you need to re-choose the desired period rather than just swipe the screen to the left/right.     

Lief app displays your actual HRV only real-time; for any previous period before now, you can see only the average HRV under a 5-minutes period as the HRV zone bar and/or average HRV during a given period (eg. a week) in Progress. Since Lief doesn’t include HR in its analytics, it only provides real-time HR data and doesn’t record your past HR for a later view/analysis.   


Considering getting an HRV monitor? 

You may find Lief uniquely valuable if you primarily want to:

  • monitor your real-time HRV while performing your daily activities, including light physical activities (Lief wearable tolerates a light sweating)
  • gain actionable insights about your HRV (i.e. what actions/situations hurt/improve your HRV)
  • get a clinical-level accurate HRV measurements
  • instantly improve your HRV through biofeedback-led deep breathing  

You may find Lief less attuned for your needs, if your primary goals are:

  • to collect detailed data about your HRV and/or HR
  • to gain insights of your HRV trends via statistics
  • to have an “all-in-one” wearable that provide data beyond just HR and HRV (e.g. activity level)

Use code EEVA at checkout to get a 5 % off from your purchase/subscription at Lief!

Use code KENKOHACKS to get 10 % off from your entire order at


Six Biohacks Japanese Moms Teach Their Kids

Growing up in Japan, I never paid attention to certain cultural teachings around me that I only now, as a grown-up living outside my home country, realise are super valuable insights into a long and healthy living.

In my conversation with Martin Kremmer, he reminded me of one of these biohacks that kids growing up in Japan naturally internalise as a part of their cultural upbringing: “Harahachibu” = literally meaning eating only 80 % full or not eating oneself full, a popular Japanese expression.

The wisdoms below may not sound completely novel per se; yet, I find that having them as well as many other cultural health adages as a part of my natural vocabulary helps me to make better and healthier choices in life. I hope that you find interesting as well as helpful lessons from my childhood from Japan when optimizing your own health wherever you live!    

Harahachibu: Harahachibu is a shortened form, and the health wisdom in its entirety goes as “harahachibume ni isha irazu”, which literally means that if you habitually eat only 80 % full, you won’t need a doctor. It was coined by Japanese philosopher Ekken Kaibara (1630 – 1714) and today commonly used in everyday conversations to remind someone with a seemingly grand appetite not to stuff themselves with foods. It’s interesting that the longevity benefit of moderate eating was already known such a long time ago that modern science now demonstrates through caloric restriction experiments!        

Naru hara ni tatari nashi: Can roughly be translated as “let your stomach rumble”, the adage tells that it’s important to eat not only moderately at one sitting, like harahachibu does, but also infrequently so that the stomach gets an idle time when it’s empty of food. Modern researches of fasting have proven spot-on this ancient observation, demonstrating that fasting improves metabolic and many other aspects of health. Additionally, it appears that the squirming movements that accompany the rumbling may help to clean the stomach and small intestine, moving forward anything left in these organs.

Yamai wa ki kara: The expression means that your frame of mind can make the course of an illness better or worse and is commonly used to encourage someone to keep a positive outlook for and/or not to excessively stress about their illness. The more knowledge I gain about stress, autonomous nervous system and their impacts on our health, the more appreciable I become of this ancient wisdom, which strikingly illustrated the importance of body’s psycho-somatic dynamics a long time before our modern understanding of neurosciences, psychology and the connection between mind and body.            

Kusuri yori youjyou: There are multiple expressions in Japan that highlight the virtue of prevention of disease over treatment, this one being probably the most often used in everyday conversations. The expression literally means “better to take a good care of oneself than to take a medicine” and often said to remind someone that it’s better to prevent an illness and/or recover from one by a proper selfcare, such as healthy eating, exercises, regular raising and bed times etc., rather than relying on medications alone. Today, I’ve became increasingly aware that the teaching of the proverb is applicable not only for physical but also mental illness; In my interview with Paris Prynkiewicz at CrookedIllness, we discuss the importance of good selfcare for mental and emotional health.     

Hayane hayaoki yamai shirazu: Often shorted into just “hayane hayaoki”, it means that “one who goes to bed early and rises early knows no illness”; Go up with the sunrise. Go to bed shortly after the sunset. Living in this way ensures that we follow the body’s natural circadian rhythm, making sure that we are exposed to the right kind of light at the right time of the day. For many of us however, this seemingly simple teaching can be tricky to implement in practice for various reasons. Additionally, most of us live in today’s world that is mal-illuminated, giving the body wrong signals for what it’s supposed to do. Can we do something about it? In my interview with Tord Wingren, founder of BrainLit, he discusses the importance of optimal indoor lighting that considers our body’s circadian rhythm.            

Warai wa hito no kusuri: “Laughter is medicine”. It sounds intuitive that laughter makes us feel great and is healthy. Sciences validate these intuitive feelings by demonstrating that laughter has quantifiable positive physiological impacts [1]. Studies show that both spontaneous and self-induced laughter are effective to reduce stress, decreasing blood pressure and cortisol level as well as increasing serotonin. How much do you laugh every day? Give yourself a 30-day challenge to laugh 30 minutes each day and see how it improves not only your psychological but also physiological wellbeing!



How Does Autonomic Nervous System Affect Health?

If you’ve been following my blog, you may already know that I’m very keen on learning about and improving my HRV through a continuous HRV monitoring. Why focus on HRV, you may ask.

It seems intuitive that autonomic nervous system (ANS), that regulates body’s vital functions like breathing, temperature and digestion, affects the rest of our body. But in which ways does it affect the body’s overall health? Does low HRV (dominant sympathetic nervous system) affect the immune system and how? Keep reading, if you, like me, have ever wondered these questions.


Try this one thing to improve your HRV instantly

After posting my first article about continuous HRV monitoring with Lief, my journey to improve HRV continues. Today, Lief is an indispensable part of my lifestyle and attaching it on my chest is one of the first things I do every morning. Seeing live impacts of an action, a habit, an event etc. on my HRV when they’re happening is so powerful, allowing me to fine tune various aspects of my lifestyle in order to improve HRV.


7 effective ways to benefit from traditional Chinese medicine (TCM) at home

I used to see a TCM practitioner multiple times per week for herbal medicines and acupuncture and believe that following a treatment plan created by an experienced TCM is the surest way of getting the most out of TCM. Effective applications of TCM much depend on the knowledge and experiences of the practitioner to customize the treatments to the patient’s specific needs. This is true with the Western medicines, too, but even more so with TCM, which approaches patients in a holistic manner.


What’s the light therapy good for?

Since my last guide about how to choose the right light therapy device, I got many questions about the benefits I’ve experienced with the light therapy.

The list of research-backed benefits of the light therapy is long and extremely versatile, including accelerated recovery from TBI, pain reduction, reduction of heart attack, improved metabolic conditions like diabetes, improved sexual function and fertility, accelerated stem cell mobilization from the bone marrow.


How to use light therapy for a glowing skin

REVISED on 26 March 2021. After my interview with Scott Chaverri, the founder of Mito Red Light, I modified my original article to reflect new learnings I gained through our talk. The original article uses 126 J/cm2 of red light as an example., which I replaced with 60 J/cm2. While the main purpose of this article is to give you the formula to calculate the desired light therapy duration at whatever dosage you want, I want to make sure that, given a wide range of dosages that appear in studies, my examples fall under a medium range of well-researched dosage range.

For a long time, I was curious about light therapy (often referred as Low-Level Light Therapy LLLT in scientific literatures) but couldn’t get my hands on it, because I didn’t feel I knew what I should be looking for. When it comes to supplements, any biohacker knows that not all supplements are created equal and can apply criteria to decide which ones are “the best”. Many might trust certain brands more than others and/or check the ingredient lists etc. When it comes to LLLT devices, though, what are these criteria that help us to distinguish the best from less desirable?

Eventually after lots of research, I decided on MitoMAX by Mito Red Light and have been very happy about it; My skin got this beautiful, radiant glow and looks much healthier than before the light therapy. I only wish that I had figured it all out much earlier and hope that you find helpful the information here, to find out which LLLT device is the best for you.

· Step 1: Decide which conditions you want to address the most. As different wavelengths are effective for different conditions, this is the vital initial step in order to narrow down the range of LLLT devices to effectively serve your needs. Among the long list of LLLT’s benefits, skin rejuvenation was one of my top interests. Researches show that wavelengths of the visible red-light range (ca 600-700 nm) can greatly increase procollagen synthesis in the skin, increasing the skin firmness and reducing wrinkles. Some of the near infrared wavelengths (750-2,500 nm) are shown to enhance cellular metabolism and effective to reduce sagginess in the lower face and neck.

Light spectrum, near Infrared outside the scale to the right

· Step 2: Decide how much time you have for LLLT therapy. Just like with supplements, knowing how much is as important as knowing which kind. The dosage of the light is expressed in Joule and tells how much irradiation the device can deliver per a specified surface area. To determine how long you need to spend in front of a LLLT device, you need the desired dosage and your device’s power density. In my case, I found a study that demonstrated a combination of 60 J/cm2 of the visible red-light and 66 J/cm2 of the near infrared light effective for skin rejuvenation. Then, on Mito Red Light’s product website I learnt that MitoMAX’s power density is 55 mW/cm2 for both the visible red-light and the near infrared light.

o Divide the device’s power density by 1,000, to convert it from milli Watt into Watt. With MitoMax, 55 mW/1,000 = 0,055 W

o Divide the dosage by the device’s power in Watt. To get the red-light dosage in the study, 60 J/0,055 W = ca 1,090 seconds

o Divide the above answer by 60, to convert the time from seconds into minutes. 1,090 seconds/60 = ca 18 minutes

And voila! Now I know that I’ll need to spend ca 18 minutes in front of my MitoMAX, to get a similar dosage of the visible red-light as in the study

Step 3: Decide which body parts you want to treat the most. By now, you’re likely to have narrowed down your list of potential LLLT devices quite a bit. As the final major step, the desired treatment areas may be equally important to consider, because in a long run, the ease and convenience of the light therapy will make a huge difference in the treatment compliance and thus efficacy. If you want to treat mostly face, neck and/or upper body, a panel that covers the entire upper body and stands on the floor can provide one of the most convenient setups, because you can be sitting on the floor relaxed and comfortably, during the entire therapy session. Of course, you might prefer standing for any reasons, but after finding out how standing still has a detrimental effect on my HRV, I’m very mindful to avoid a long still standing when possible. If your main treatment area is the lower body, and you prefer not to stand for a 15+ minutes treatment session, you may want to get a model that allows a horizontal fixation, so that you can be lying down on you side during the therapy.

Other things to consider: For many, EMF and flickering can be important concerns. Some manufacturers provide information about their products’ EMF and flickering levels on their webpages, while others don’t, so you might need to contact them to ask them about their devices’ EMF and flickering levels. In my interview with Scott the founder and CEO of Mito Red Light, he addresses with a depth both EMF and and flickering, including what EMFs are, whether you should be concerned about EMF from a light panel, and how Mito Red Light has addressed them.

As I live in Europe, and many manufacturers are US-based, a low-cost, hassle-free international shipping was a must, and I’m extremely happy with my experience with Mito Red Light; the shipping cost was very reasonable, and the panel arrived in just few days after the order. A domestic shipping could have taken longer!

I hope you find useful the table comparing some major light panels for the required time for 1) a red-light therapy at 60 J/cm2 dosage and 2) a near infrared therapy at 66 J/cm2. Please note that I’ve taken into account the power density in particular wavelengths; For instance, if the (total) power density is 110 mW/cm2 in the manufacturer’s spec, and the ratio of red light and near infra light is 50:50, the adjusted power density for each wavelength category is 55 mW/cm2.

Give the code kenkohacks at checkout to get 5 % off your entire purchase at Mito Red Light!


Are you missing out on benefits of anti-aging powerhouse seaweeds? What to do if you don’t eat them

Sushi is becoming ever more popular outside its home country, but many traditional Japanese foods can still strike somewhat mysterious outside their country of origin, like mud-covered burdock roots, fermented soybeans natto, and various types of dried and fresh seaweeds, to mention a few. Personally, a thought of these delicious foods makes my mouth water, but often, their culinary charms are lost in translation, and I find myself eating them alone, while my Swedish fiancé munches his meatballs.

But if you are like me and acknowledge foods’ powerful impacts on our health – are you missing out some unique benefits of foods like seaweeds, if your diet is absent of them? Maybe.

Many researches demonstrate that seaweeds, like wakame and kelp, have a wide rage of health benefits such as:

· Great for skin: Phlorotannin, a type of tannin found in brown algae such as kelps, is a potent antioxidant and photoprotective agent, absorbing harmful UV radiation in a similar manner than another, perhaps better-known, marine compound astaxanthin [1]. If your skin already shows some signs of photodamages, they also have a skin whitening effect, improving UV light-caused hyperpigmentation. Laminarin, a type of carbohydrate in kelp, is shown to stimulate the synthesis of the dermal tissues, potentially reducing wrinkles.

· Great for hair: ”Seaweeds are good for the hair” is a common folklore belief in Japan, and science seems to agree with the ancient wisdom. A 2012 study showed that Grateloupia elliptica, a seaweed related to one of Japan’s favorite seaweeds, nori (seaweed that covers a rolled sushi), has the potential to treat alopecia, inhibiting the enzyme 5 alpha-reductase and decreasing lipopolysaccharide-induced pro-inflammatory cytokines. Though I’m unaware of a commercial product including an extract of this promising seaweed, incorporating in your diet a high-quality organic nori, like this one, certainly won’t hurt.

· Promotes anti-inflammatory immunity profile: Among numerous beneficial compounds in seaweeds, I’m personally most excited about fucoidan, a complex polysaccharide responsible for the gel-like consistence of many seaweeds. Researches show that it’s a powerful immunomodulator, shifting the immune system from a pro-inflammatory configuration (upregulated interleukin 6, 8 cytokines and upregulated TNF-alpha) to an anti-inflammatory one (upregulated interleukin 10 cytokine). Many in vivo animal studies demonstrate its ability to reduce a systemic and chronic inflammation in a wide range of animals and conditions, such as diabetic mice, mice and rodents with chronic rheumatoid arthritis, and rodents with liver damage [2].

In this time of pervasive stress and resulting chronic whole-body inflammation, most of us unfortunately live in, I feel that adding to one’s regimen a potent anti-inflammatory immunomodulator like fucoidan can be a fantastic strategy. On top of a daily munching of my favourite seaweed dishes, I take a fucoidan supplement, to ensure a daily intake of 300 mg fucoidan, a dosage used in many human fucoidan trials.

· Anti-cancer properties: I’m not a medical professional and usually don’t write about cancer. I lost my Dad for a lung cancer at the age of six; Having experienced personally how devastating the disease can be, I don’t want to make any light-hearted statement about such a serious medical condition. However, I feel that I may be amiss to leave altogether fucoidan’s anti-tumor properties, one of the most researched areas for fucoidan’s benefits. Multiple researches demonstrate fucoidan’s anti-cancer effects through several mechanisms; including cancer-cell apoptosis, inhibition of angiogenesis in cancer cells, and immunomodulating effect mentioned above [3].





No sauna? No problem! How to upgrade your hot bath to a super biohack

Sauna, a tradition in many Nordic countries especially in Finland, has recently enjoyed a renewed status as a biohack that not only makes us feel good, but also is good for us, improving and optimizing various aspects of our mental and physical health, such as cardiovascular health, mood disorders and recovery from exercises. Indeed, I’m bummed that in Sweden, my current country of residence, this wonderful tradition is not nearly as ubiquitous as in Finland, my previous Nordic residence. Previously, I was trying to convince my Swedish fiancé to upgrade our home with a proper dry sauna, or at least an infrared sauna, to not miss out this seemingly omnipotent biohack.

They are notoriously expensive though, costing easily thousands of euros. Also, they require space, a deal-breaker if you live in an apartment, like we do, rather than a detached house. As the realization set down that moving to a large house just to enable occasional sauna sessions probably is an unwise and unnecessary extravaganza, I took a serious look at another wonderful tradition from my home country, Japan – nyuyoku i.e. whole-body immersion hot bath.

Both sauna and hot bath take an advantage of the heat’s beneficial effects. One of the best-known benefits of heat immersion is improved vascular functions, such as decreased blood pressure and improved arterial stiffness [1]. Heat immersion can also act as an effective exercise mimetic, upregulating nitric oxide synthesis and increasing angiogenesis, great news to those with an injury preventing pulse-raising activities. To my great joy, studies demonstrate similar health benefits across different heat-delivery methods, and in a 2018 paper, a group of Japanese researchers reported that habitual hot-water bathing has protective effects on cardiovascular health, like these achieved with dry sauna [2].

Not only matching the benefits of sauna, immersive bath has some unique benefits, such as water pressure and buoyancy [3]. Researchers who are proponents of whole-body immersion bathing tend to underline these additional benefits, like increased cardiac output and increased metabolism induced by water pressure [3].

For a homebrewing biohacker like myself, however, hot bath’s greatest edges probably are its availability and “stack-ability” i.e. hot bath can be stacked with many other biohacks. Let’s explore how we can stack a hot bath to upgrade it to a next level super-biohack.

No story of bathing in Japan will be complete without a mention of the ancient tradition onsen, a whole-body immersion hot bath in therapeutic spring water. It’s such an important tradition that a federal law onsen hou regulates it, requiring that any water source that calls itself a legal onsen satisfy criteria such as the presence of certain minerals and/or other therapeutic agents at specific concentrations. For instance, manganese, bromine, and irons are onsen-making minerals at specific concentrations.

At home, many Japanese add bath salts to their bathtub, such as this one and this one, containing mineral blends like these found in well-known onsens. Some onsen waters are also drinkable, and many believe that the oral intake has additional health benefits. While I’m unaware of a scientific evidence supporting the believe for oral onsen consumption, benefits of mineral absorption through the skin are thoroughly documented, making it a great stacking strategy to spike your bath water with a high-quality onsen bath salt.

Also, some gases and even certain types of radiation are recognized as one of 19 onsen-making therapeutic agents. My current bathing routine involves a mineral-rich onsen bath salt combined with molecular hydrogen bath tablets. I’m a big fan of hydrogen water and have tried many different products as well as different ways of administrations. I started adding hydrogen tablets to my hot bath after learning that Dr. Ohta, the chief author of the 2007 Nature Medicine paper [4] that triggered the increased interests in hydrogen as a therapeutic molecule, is a big proponent of hydrogen bath and that just a 7-minutes of immersion in hydrogen gas-rich water is shown to increase the body’s hydrogen level.

The triple-stacks with heat, minerals, and hydrogen gas make me feel golden every evening when I take a half-an-hour or so hot bath! Nevertheless, I’m curious to further add a radiation therapy to my already well-stacked hot bath practice. Since an American researcher Dr. Luckey’s 1980 publication “Hormesis With Ionizing Radiation”, describing hormesis effects of a low-level radiation, over 3,000 scientific research papers have demonstrated low irradiation’s benefits across species including humans [6]. Among the benefits are increased SOD (super oxide dismutase), increased GPx (glutathione peroxidase), and an increase in T immune cells. In Japan, onsens with a low level of radon have been appreciated as therapeutic over 1,000 years, and today, pieces of rock from these onsens are available for purchase, to recreate the beneficial irradiation at home.

So, I’m feeling ok without sauna at home after all. Though it’d be nice to have one, the researches seem to point to that hot bath is at least as good a biohack, with the bonus of multiple stacking possibilities!

Upgrade your hot bath to a super biohack with
Mineral-rich therapeutic onsen bath salt
Hydrogen bath tablets
Radiation generating onsen rock

[5] Luckey T.D. Hormesis with Ionizing Radiation. Boca Raton: CRC Press, Inc.; 1980.