
Frequent sauna bathing can reduce the risk of dementia - upen
http://sciencebulletin.org/archives/8286.html
======
louprado
There is similar study that showed a positive correlation between longevity
and sauna use. Dr. Rhonda Patrick made the following comments its defense
which I have pasted below.

Most of the dismissing comments have a few common themes...

1.) They underestimate the prevalence of sauna use in Finnish culture, where
the study was conducted. Finland has a population of around 5 million people,
but has around 3 million saunas. Sauna access is ubiquitous and not strictly a
marker for socioeconomic status.

2.) They disregard the fact that physical activity was adjusted for. In other
words, sauna use wasn't simply correlated to overall physical activity in this
case.

3.) They assume that because sauna use is correlated with longevity (after
variables are adjusted for) that we should expect Finnish folk to live as long
as the trees. In actual fact, while sauna use is probably a healthy habit...
the Finnish have habits that undermine their health just like any other
country.

4.) They forget about the evidence in lower organisms. In flies and worms heat
stress (exposing them to a 30 min. heat chamber just one time) has been shown
to boost lifespan by up to 15%. This effect was shown mediated by heat shock
proteins (hsps), which are very robustly increased in humans during sauna use.
I don't know for sure that the Finnish sauna longevity study has anything to
do with an effect from HSPs... but it stands to reason! The fact that lifespan
extension was demonstrated in two very different lower organisms also means
that this effect is highly evolutionarily conserved.

5.) They also tend to forget that humans that have a gene variant in heat
shock protein 70 that makes it active all the time have a significant increase
chance of living to be a centenarian (at least 100 years old).

For those interested, here's the sauna longevity study in question...
[http://www.ncbi.nlm.nih.gov/pubmed/25705824﻿](http://www.ncbi.nlm.nih.gov/pubmed/25705824﻿)

~~~
Fnoord
( __snip __)

Do people socialise whilst being in a sauna, or do they rather meditate? Does
it differ per person or region? If meditate, has there been cross reference
between people who meditate instead of sauna?

~~~
ptaipale
Socialising and meditation differs per person, not really by region in
Finland.

Mostly the sauna is a family thing (yes, the whole kernel family of parents
and small children may go together to their own sauna, everyone's naked, until
the children are close to puberty and men and women of family go separately;
public saunas such as those in swimming halls or the traditional public
washing facilities are strictly gender-segregated.)

Sauna is perhaps a bit more of a social happening than meditation, although
there are some clear aspects of meditation as well. As of old, sauna is a
"holy" place; you're not supposed to yell, as the house-elves would not like
it. In traditional farms, sauna was were babies were born, and where the dead
were washed, so it's a bit of a place of reverence. And it used to be the
cleanest and often warmest part of the household.

~~~
pimeys
Then again all of my friends go to Sauna together, men and women, naked. There
are some famous public saunas where you can do this, especially the now famous
Sompasauna in Helsinki.

Source: I used to live in Finland.

~~~
ptaipale
Yes, it happens, though it's definitely not the norm.

Most often this occurs with young university students.

~~~
pimeys
Don't forget the hippies... :)

------
serpix
As a Finnish person this question makes no sense. Everybody goes to the sauna.
The young, old, babies, the sick as well. I go to the sauna even with fever as
it feels good with the chills.

~~~
wyclif
It's tough to go to the sauna in the USA because it's rare that health
clubs/gyms have them. Particularly since the advent of "box" type gyms that
imitate Crossfit.

~~~
tass
And that requires a gym membership.

There is no such thing as a standalone sauna that's not also a pickup spot,
though would love to be proven wrong.

~~~
blackguardx
There are a few in SF.

Archimedes Banya (www.banyasf.com/) is my favorite. They have a real Finnish
sauna that gets up to 100 C (or over) along with a pool for cooling off that
is less than 10 C. They also have two Russian baths and a Turkish bath (steam
room). To get that real Finnish/Russian experience, you can even bring your
own alcohol. Clothing is optional on one half and required on the other.

There are others in SF, but I haven't been to them.

------
zo7
I wonder if taking a hot bath can have the same effect. I've been taking them
more frequently recently and I've definitely noticed that my heart rate goes
up (and that I smell a bit different than after taking a shower, presumably
because I'm sweating more). I've been debating whether or not it's actually a
healthy thing to be doing, but it's definitely relaxing and makes you fall
asleep faster at night as it's getting colder in the winter.

~~~
dao-
Probably has both good and bad side-effects. As someone with dry skin I'd
prefer sauna over hot baths with soap.

------
brenfrow
I wonder if the frequency of going to the Sauna was tied to the frequency of
going to gym to workout? Here in Seattle that is basically the only place you
can go to find a sauna.

~~~
fsloth
There is a sauna in nearly every house in Finland, and if not, then municipal
swimming halls offer an affordable alternative which everyone can afford. No
need to join it with heavy exercise. Also, going to a sauna does not signal a
socioeconomic status.

~~~
pbhjpbhj
Is there no charge for municipal facilities?

It's amazing if Finland has solved poverty to the level that every household
can afford to set aside the space for a sauna and costs of running it.

In the UK heat poverty is a widespread problem due to the costs of heating
fuels. Presumably saunas are being run from geothermal sources to make it
cheap enough??

I'm assuming saunas are cupboard sized, is that accurate or are all these
homes dedicating a full room of space?

~~~
dharma1
The prevalence of saunas in Finland is mainly because it has been a part of
the Finnish way of life for thousands of years, not an exotic luxury in the
way it might be perceived in some other countries.

Municipal facilities (swimming halls with saunas etc) are charged, probably
about 4 euros per visit, with discounts for students and elderly.

The saunas people have in their homes these days are typically electric.
Electricity prices are roughly the same, perhaps a bit less than UK - an hour
of sauna with 4kw stove would probably cost around 0.5 euros in electricity.
Some apartment blocks have shared saunas you can book for free, some have
small saunas in each apartment. In detached houses you typically get a bit
larger saunas.

In general access to saunas is widely available for everyone regardless of
socioeconomic status, and there is less economic inequality in general
compared to the UK.

Heating is a separate topic but I'll reply briefly - majority of housing in
Finland is heated with district heating, rather than individual gas boilers in
each house, like in the UK.

[https://en.wikipedia.org/wiki/District_heating#Finland](https://en.wikipedia.org/wiki/District_heating#Finland)

As a result, heating tends to be cheaper for consumers compared to the UK.
Also, Finnish housing tends to be much better insulated than housing in the UK
(because of colder winters).

Outside cities, where population is sparse, people heat their houses with
electricity/wood/oil/geothermal - with many new builds now opting for
geothermal.

~~~
ptaipale
Just a note about district heating: it's not majority of all housing (market
share somewhere around 45 %), but it is majority of new housing (around 60 %).

See
[http://energia.fi/files/799/Lu_Kostama_Mikkeli.pdf](http://energia.fi/files/799/Lu_Kostama_Mikkeli.pdf)
slide 10.

And saunas are heated with electricity in towns, although a few old public
facilities still run on wood stoves, as well as private saunas of those who
like the "pure" feeling (such as myself).

------
abakker
Possibly related to dilating capillaries? Seems like my lasting impression
every time I go into a sauna is that I get completely flushed, and that
generally feels good. Maybe it proxies some of the benefits of cardio
exercise?

~~~
manmal
My own hypothesis is that sweating helps the system get rid of heavy metals,
which seem to play a part in dementia (e.g. aluminum > Alzheimer).

~~~
sitkack
The heat kills the fungus which just happens to be collecting aluminum.
Aluminum is most likely not a _cause_.

~~~
pbhjpbhj
Interesting, is that hypothesis research backed, any citations to share.
Alzheimer's is an apparent family trait I'm keen to avoid.

~~~
jnicholasp
I'm in the same familial boat. Have you looked into lithium supplementation
yet?

------
malydok
I wonder if this extends to hot spring usage as well, in Japan for example.

~~~
ekianjo
Japan has a large percentage of senior dementia patients so this study seems
very doubtful.

~~~
coldtea
It could still have much less senior dementia among those Japanese going to
the hot springs compared to the vast majority that doesn't go.

------
hannob
This whole text is such a prime example of what's wrong with science
reporting.

In the very first sentence a causal relationship is claimed ("Frequent sauna
bathing can reduce the risk of dementia"). Yet the whole article doesn't live
up to that claim, because it is very clear that the study purely relies on
observational data and thus may very well just have found a confounder.
However it doesn't even bother to mention or discuss that limitation.

~~~
coldtea
And this comment is a prime example of what's wrong with internet comments on
scientific research.

Usually all the basic concerns have been accounted for in the actual study.

Whether an article in the mainstream press conveys that or not, is not
important, since the article is just supposed to give a summary of the
findings.

It's seldom an issue of "those stupid PhDs and experts in their field, they
didn't think of a confounder a random internet person can come up with in 5
seconds".

Whoever wants to delve in can read the actual reports.

And whoever wants to start the same practice (e.g. sauna here) would be
foolish to do it based on one article anyway, they should consult with their
doctor, and/or wait until a fuller consensus has been reached after several
meta-studies (which can take decades).

~~~
hannob
> Usually all the basic concerns have been accounted for in the actual study.

No. It's an observational study. If they'd account for the basic concerns
they'd do an RCT. Yes, that's more work and takes longer.

> It's seldom an issue of "those stupid PhDs and experts in their field, they
> didn't think of a confounder a random internet person can come up with in 5
> seconds".

No, you don't understand the problem. Confounders everyone can come up with
can be controlled for (although it gets complicated the more you consider).
But the major problem are unknown confounders. You can't control for things
you don't know.

~~~
timr
"Observational study" does not mean "bad science". There are good and bad
observational studies, and without _reading the paper_ , you can't know which
one this is. Moreover, your assertion that only random trials can be
controlled is just completely wrong - there are plenty of ways to do
controlled studies on observational data. You're engaged in the scientific
version of the middlebrow dismissal.

In health sciences, a lot of good work starts as well-controlled observational
science. In fact, for a question like _" does sauna use lead to a reduced risk
of dementia over a human lifetime?"_, pretty much the _only_ way you're ever
getting the funding to do an "RCT" is to start with lots of observational
evidence.

~~~
ptaipale
Yes, observational study does not mean bad science. But claiming or inferring
that causation was found when it was not, that's bad science reporting.

~~~
timr
Never said anything about the reporting. The headline is certainly bad. But a
bad article doesn't mean bad science.

------
koolba
Would regularly taking long showers have a similar impact or is the
temperature shift not enough?

~~~
shostack
That would be an amazing excuse for finally justifying my contribution to our
water bill.

------
tsao
People who go to the sauna frequently might be more social or get more social
interaction.

~~~
coldtea
Not in Finland, where the study was conducted, and where almost everybody has
a private sauna.

------
mcv
I saw the headline and thought: This is the best news ever! I love saunas, but
I don't even come close to once a week. It's a special treat for us that we do
maybe once every few months. To do it daily or weekly, it needs to be part of
your routine, and really close to home.

But if the Finns really sauna this much more often than anyone else, then
there should also be a noticeable difference in dementia between Finnish
people and anyone else.

------
riprowan
Seems like you could do a great confirmation study with participants in Bikram
/ hot yoga where the temps are 105F for 90 mins with ~50% humidity.

I'm going to go out on a limb and say the sauna cohort and the Bikram cohort
are two extremely different sets of individuals with lots of different
behaviors, so if the same effect was found in regular Bikram yogis a lot of
variables might be able to be eliminated.

~~~
vurpo
Saunas are much warmer than that. Regular sauna temperature in Finland is
around 60°C - 90°C (which is around 140-190°F). This is the air temperature at
which pretty much everybody goes to the sauna here, including the young, the
old and sometimes even the ill.

~~~
riprowan
Fair enough to make the comparison perhaps a poor one. However I don't think
that people do yoga in saunas, but rather remain seated, correct? The point
I'm getting at is: isn't the question "what's the net rise in body
temperature?" In hot yoga, the room isn't as hot as a sauna but you're
exercising strenuously, so that the body becomes about as hot as you can
safely heat a body, kinda like a sauna.

------
desireco42
And lets all do sauna bathing all the time. :) If they discover that reading
HN, we will totally feel justified.

------
matwood
I live in the south and even though it gets hot and humid in the summer, it
does not sound like it's hot enough to shock like this study proposes. I
mostly enjoy the heat and humidity. When I lived out west in a much drier
climate, my gym had a sauna that I used almost every day.

~~~
kaitai
When I sauna, we usually like the sauna at about 180 degrees Fahrenheit, and
that's usual for Finns. The heat difference is enough that even when it's
90-100 degrees F in the summer (and humid) where I live, it's nice to take a
quick sauna as it makes the rest of the evening feel much cooler in
comparison!

------
Tempest1981
Would a hot tub have a similar effect? I'm not really sure how or where I
would install a sauna.

~~~
dharma1
Possibly, definitely in terms of relaxation, but in terms of heat shock I
don't think so - Saunas in Finland tend to be heated quite hot - usually 70–80
°C, sometimes more.

Installing one isn't too difficult - if you have a garden, you can get outside
kits which are generally as simple to build as sheds, or indoors kits that
you'd put in a bathroom - probably when doing renovation anyway. I recommend
ones from Harvia - I bought a medium sized one (fits 4 people) for about £1600
in the UK, and it took me and a couple of guys less than a day to put up.

Here are some pics - I built it as a part of a loft conversion and ended up
tiling the outside so it looks like a part of the bathroom. Normally these
prefab kits look like a softwood cladded mini-room from both inside and
outside

[http://imgur.com/a/MNEFD](http://imgur.com/a/MNEFD)

The stove is usually 4kw-8kw so you'll need to add appropriate wiring and
fuse/breaker.

If anyone is contemplating building one, feel free to ask me for advice.

~~~
rwmj
You don't actually get in the water at 80°C right? I assume that would either
kill you or severely burn.

~~~
pasiaj
You can easily go to a sauna with temperatures exceeding 110° C. Hot as heck,
but even kids do it.

The starting temperature of World Sauna Championships was 110° C, with
water/steam added every 30 seconds. The competition ended up killing a person,
tho.

[https://en.wikipedia.org/wiki/World_Sauna_Championships](https://en.wikipedia.org/wiki/World_Sauna_Championships)

~~~
userbinator
I'm surprised that sweat doesn't start boiling at that temperature, or that
the users don't get severely burned since I assume everything in the sauna is
going to be around that temperature --- even 50C is enough to burn skin:

[https://en.wikipedia.org/wiki/Thermal_burn](https://en.wikipedia.org/wiki/Thermal_burn)

~~~
kaitai
My sauna last night was 84 C, 183 F. I personally don't like much hotter. The
higher the temperature, the more you have to modulate the steam that you
produce by throwing water on the stove. At a lower temperature I like lots of
steam, but at higher temperatures a lot of steam at once can be too much.
Steam is controlled by the users on a moment-by-moment basis while temperature
is controlled more slowly by the stove settings (which of course you can
change).

The wood in the sauna does get hot: that's why you either sit on a piece of
cloth (more popular these days) or put cool water on your seat to cool it down
so your butt doesn't burn. However, wood in saunas is generally carefully
selected as some varieties feel cooler than others (and you _never_ want to
use a wood that will produce sap drips for your benches! ouch!!). There are
almost no metal components to touch in a sauna because those hurt -- some
people use copper buckets for water but then you're filling it with cool water
intermittently.

Take off metal necklaces and earrings before saunaing, in general. Don't know
about piercings (someone else can say). You can cook/burn yourself in a sauna
but that is usually related to drug and alcohol use (as in the famous World
Sauna Championship death:
[https://www.theguardian.com/world/2010/aug/08/sauna-
champion...](https://www.theguardian.com/world/2010/aug/08/sauna-championship-
russian-dead))

~~~
jpatokal
Yes, metal piercings also get hot. Cold water helps.

------
mtw
Is it possible that those undertaking frequent sauna bathing have overall
healthier life habits? They might exercise more, eat better and sleep better
than those who do not

------
ekianjo
protects? thats not proven, this studies implies onlY correlation and it could
still be very much a random result or there coulf be multiple factord not
taken in consideration

~~~
fnl
I couldn't agree more - its worrisome how many people still jump to causal
conclusions from this kind of study...

------
watchdogtimer
Could this also explain why regular vigorous exercise (which also raises your
body temperature and causes you to sweat) is good for your health?

------
Casseres
I just did a little research into the benefits of sauna use. I found a Reuters
article published in 2015 which said, "men who spent time in a sauna seven
times a week were less likely to die of heart problems or to die at all" [0].

So good news everbody: If you use a sauna seven times a week, there's a chance
you could become immortal.

[0] [http://www.reuters.com/article/us-heart-health-saunas-
idUSKB...](http://www.reuters.com/article/us-heart-health-saunas-
idUSKBN0LR1LP20150223)

------
jey
Or is it just that healthy people can use the sauna more frequently?

~~~
knodi123
or in other words, "Maybe these researchers are absolute morons."

~~~
SomeCallMeTim
I do wonder if there was a confounding factor that they didn't successfully
isolate. "General health" seems like an obvious one, but some other factor
might be more subtle.

~~~
pg314
From the abstract: _analysis [was] adjusted for age, alcohol consumption, body
mass index, systolic blood pressure, smoking status, Type 2 diabetes, previous
myocardial infarction, resting heart rate and serum low-density lipoprotein
cholesterol_ [1]. Of course, that doesn't rule out all confounding factors.

[1]
[http://ageing.oxfordjournals.org/content/early/2016/12/07/ag...](http://ageing.oxfordjournals.org/content/early/2016/12/07/ageing.afw212.abstract?sid=6d9f2e72-6503-48c2-b63f-1dc27c24859f)

------
DoodleBuggy
So is it the heat, or the sweating, or something else?

------
chrismealy
It would be hilarious if that baloney about "releasing toxins" was true for
once.

------
partycoder
But sauna affects your fertility temporarily.

------
erertooker
All this is concluding is that of recreational activities spending time in the
sauna is less harmful than the likely alternative ways people would fill that
time.

------
sporkologist
I'd bet that frequent yachting is also healthy.

~~~
zmb_
The study was done in Finland. There are estimated to be 2-3 million saunas
for a population of 5.4 million. Majority of the population has access to a
sauna at home. It is not a luxury.

~~~
wyclif
Around how much would it cost on average in the US to install a sauna?

~~~
kaitai
From $1000 to $5000 depending on size, luxury, and how much you do yourself vs
hire out. There are a few things you want to be knowledgeable about if you do
it yourself: moisture barriers and management, what kinds of woods to choose
and what not to choose both for durability and comfort, and some understanding
of stoves & rocks especially if you're picking your own rocks -- some types of
rocks are prone to exploding and that's unpleasant.

You can buy prefab kits (so the moisture barrier is built in and the benches
are pre-assembled) from companies like Finnleo, or you can buy a stove alone
from tons of places. Just make sure you're buying a stove that is truly meant
for a sauna (throwing water/making steam) instead of a heater for an infrared
room (different!).

