Who wouldn’t love to become immune to the cold? Walking around in the snow with just a bathing suit. Taking a dip in an ice-cold lake with a smile on your face. Meditating under a waterfall in winter.

That alone is a pretty sweet achievement. It’ll get you free drinks in a bar — and more if you’re lucky. You’ll be a true badass. You might even be able to survive the maiden voyage of the new Titanic.

But I found a way to use the WHM to get something more valuable than these cool stunts. Far more valuable. Finally, after a long year of failed attempts, the cold fixed my deep sleep.

Fear of the cold

A few years ago, I discovered Wim and the WHM thanks to Tim Ferriss. I was instantly hooked by the crazy possibility of controlling my autonomous system, and promised myself to try it soon.

“All” I needed was to get comfortable with trying to take cold showers. Minor problem: I've always been very sensitive to cold water, far more than the average person.

So you can guess what happened… A few years quickly passed by, and here we are!

First contact

One night this past fall, a few days ahead of a WHM training with Wim, I decided to face off with my old nemesis: cold water.

I was inspired by Wim's spirited dancing in the cold shower on his free video, and that broke my old mental block. He was having so much fun doing it… it couldn’t be that bad!

I followed his instructions to the letter. Warm shower, then turn it off. Prepare yourself mentally, turn on the cold water, start with hands and feet, then shoulders, then back, then everything.

I won't lie to you: I did not exactly enjoy it. It was cold, alright, and I forgot to have fun dancing in the shower. But I was proud of my accomplishment, and I went to bed with a sense of a job well done.

I’m often shivering when I first get under the sheets in fall and winter, but strangely I did not feel cold. The sheets felt cool, and it was not bothering me. It felt as if I was a cold-blooded animal.

I also expected to have trouble falling asleep. The cold water right before bed had woken me up like a smack in the face. Quite the opposite of what I had been doing right before then, gently powering down with low lights and no screens. I walked out of the shower feeling 100% alive and ready for action! And yet, surprisingly, I fell asleep just as quickly as usual.

But the real surprise — the shocking surprise — waited until the morning.

One ring to rule all nights

Let me backtrack for a minute. You see, I wear an Oura ring.

What's that? Not an invisibility gadget that will get you in trouble with the Eye of Sauron.

My Oura ring

It’s a wearable device that tracks your activity but, more importantly, can analyze your sleep in precise detail. They claim to be the most accurate sleep analyzer (except for clinical equipment), and lots of serious biohackers swear by it. These are good enough credentials for me.

You might be wondering: why do I care about analyzing my sleep, and more importantly: why should you?

Because we are discovering that sleep is a dominant factor influencing your health; arguably even more important than stress management, nutrition and exercise. That’s why sleep has recently become one of the hottest health topics.

Getting quality sleep produces a long list of impressive, almost too-good-to-be-true benefits… a bit like the WHM! For more on this, read Matthew Walker’s book Why We Sleep.

Our bodies are amazing machines that can recharge and repair themselves, but they need proper down time to do that well. Most of us routinely deny our body the sleep it needs, so we deplete our resources, stop functioning properly, perform less well, and eventually can get really sick.

You get what you measure

I got my first Oura ring over a year ago, after Kevin Rose recommended it based on Peter Attia’s advice.

Right away, it became clear why I was routinely waking up feeling tired, even with a decent amount of sleep (like 7 hours). The reason: not enough deep sleep, and sleep interruptions (wake-ups). Deep sleep is the most restorative type of sleep, so a lack of it is particularly damaging to your well-being.

Typical night: problem with deep sleep (and tranquility).

(Sleep cycles: white = awake, light blue = REM sleep, medium blue = light sleep, dark blue = deep sleep.)

Great, I thought, let me fix that!

Knowing the problem is half the battle. So I read the advice provided by Oura on its app, listened to a bunch of podcasts, scoured related blogs, and attempted to follow it all.

Over the past 14 months, I have tried countless tactics to improve my deep sleep, including:

no eating after sundown

cool, pitch-dark room

no coffee after 10AM

no screens two hours before bed

no exercise at night

no blue light, low light in the evening

consistent sleep schedule

wearing socks, or long sleeved pajamas

various sleeping pills

teas with mushrooms (Reishi, Lion's Mane, ...)

One after the other, each technique failed to show any major and consistent improvement in my deep sleep. Sure, there were a few wins here and there, but nothing both clear and reproducible at will. (Of note: I found that going to bed by 22h00-22h30 does help consistently but offers only modest gains.)

It’s been very frustrating.

Breakthrough

But the morning of October 9, after my very first night taking a cold shower right before sleep, I woke up before my alarm, feeling rested.

I powered up my phone, opened the Oura app, waited for it to sync with my ring and... surprise: record-breaking deep sleep! 1 hour 51 minutes. More than twice the 40-50 minutes I typically get!



Success!

Deep sleep = dark blue at bottom

At last, here was a result that clearly stood out from the noise!

But I was trained as an engineer and scientist, so my excitement quickly turned into suspicion. Perhaps it was a coincidence. I had been tired for several days, and maybe I was overdue for some deep sleep and this would have happened anyway.

So I decided to not take a cold shower the following two nights. Next morning, I felt good but saw that my deep sleep was back to a normal level. Same thing the following day.



Deep sleep back to normal levels

On October 11 came time to run the experiment again with another (painful) cold shower before sleep. I also had just finished working on my computer, and feared I might have ruined the experiment with such a classic mistake (screens near bed time).

But the next morning, I stared at a new, even higher record amount of deep sleep: 1 hour 55 minutes! I could not believe my eyes.



Another win!

(Deep sleep = dark blue at bottom)

These pics are from the phone app. Oura also has a cloud web site where you can view your data a little better. This chart showing only deep sleep demonstrates my experiment even more clearly.

Both peaks in deep sleep more clearly stand out

A magic bullet?

That week, it seemed that I had finally cracked the code for deep sleep. I thought a cold shower would fix my deep sleep problem, no matter what else I did.

But I soon realized that’s not quite true. Basically, the other factors still affect my sleep.

Here is what I have learned since then, by doing many more experiments and keeping track of my results:

A cold shower before sleep is not a guarantee to get great deep sleep. It will not save you from doing all the things you’re not supposed to do. For example, if I eat + drink + exercise at night, and go to bed late, I end with little deep sleep. Also it seems that high stress damages the benefit from cold showers.

damages the benefit from cold showers. Cold showers are not the only way to get deep sleep. Looking back over the past 13 months, before I started WHM, I saw a number of nights with really good deep sleep. No idea what caused them though, as they are spread out seemingly randomly. But with cold showers, great deep sleep went from rare to frequent.

Repeated cold exposure seems to have a protective effect for my deep sleep. I used to get many nights with almost no deep sleep (15-20 minutes), and that has not happened since I started WHM.

So even though you cannot violate all the rules of good sleep, cold showers remain the best weapon I’ve found for getting lots of deep sleep. When used in conjunction with the other guidelines, it seems to produce great results.

Time for action!

Let’s be clear: my experience does not constitute a scientific proof or study. I’m still testing every day to better understand the separate impact of cold showers before sleep vs. other factors.

I know that there is still a lot more to discover, because I’ve had a few unexplained counter-examples on both sides. A few times I got disappointing deep sleep despite “doing everything right” (as far as I can tell). And a few times I “behaved badly” and still got great deep sleep. So I’m still refining how this all works, and I might report on new lessons learned in the future.

But the results so far are very encouraging. The pattern of success is clear, despite these exceptions. I’m telling everyone about it— and now you know too! If you struggle with sleep quality (i.e. waking up feeling tired after a decent night), you simply can’t afford not to try this simple hack.

So promise yourself to give it a shot tonight and for the next few days. Try it 5-10 times, in a row or on-and-off, and report your findings here so we can learn from you too.

If you practice the WHM, you get this “for free” since you’re taking cold showers anyway, right? Time it right before going to sleep, and watch your deep sleep soar!

Thierry Marbach is an entrepreneur and lifelong learner.

Photo by Matthew T Rader on Unsplash