Here is for example an article on sauna that I have read:
 https://pdf.sciencedirectassets.com/271341/1-s2.0-S0531556521X00095/1-s2.0-S05315565210029[…]lY3QuY29t&ua=0a0b560605045c52&rr=9aad34daa873be38&cc=dk
For what I understand, is that there is no extremely hard evidence for benefits of sauna/icebathing, but there is a lot of research that points in that direction.

Someone I know sent me this. Here is my reply on 13 December 2025 covering the study, which I think is in the spirit of Seth's post.

Thanks for sharing, [name]! To clarify, I was mostly sceptical about the ice bathing (I looked into this a bit because my father does 10 ºC bathing sometimes, and was claiming it has lots of benefits). I have now looked into the study above ("Sauna use as a lifestyle practice to extend healthspan"). I think the evidence presented there is very weak. In terms of data from interventional studies, which involve comparing a group which receives a treatment (like more sauna) with a control group, and are the type of study which offers the strongest evidence, they mention the following (I searched the paragraphs with "interv"):

• "Findings from a small intervention study in rodents demonstrated that local heat application during an immobilization period decreased muscle atrophy by 37% compared to a sham treatment". Very weak evidence because it is about rodents.
• "A randomized controlled trial that examined the effects of sauna use in 24 patients with ischemic heart disease with chronic total coronary artery occlusion who had not responded to non-surgical procedures and had failed or were not candidates for percutaneous coronary intervention demonstrated that 15 waon sessions given over a 3-week period improved the patients' vascular endothelial function as measured by flow-mediated dilation of the brachial artery. No significant improvements were observed in the control group that received standard medical care (Sobajima et al., 2013)". Very weak evidence because:
  • The sample size is tiny (24 people in the treatment group).
  • The treated people are very special people (so sauna being beneficial for them does not imply it has benefits for a random healthy person).
  • They did not measure mortality (I do not know the extent to which this correlates well with "flow-mediated dilation of the brachial artery").
• "A small intervention study investigated the effects of repeat sauna use on endurance and other physiological effects in 6 male distance runners. The findings showed that one 30-minute sauna session twice a week for 3 weeks post-workout increased the time that it took for the study participants to run until exhaustion by 32% compared to their baseline". Very weak evidence because:
  • The sample size really is super small (6 people)!
  • The treated people are not random people (they are distance runners).
  • They did not measure mortality (I do not know the extent to which this correlates with "time that it took for the study participants to run until exhaustion").
• "Another randomized controlled trial found that endurance training in a sauna suit led to improved performance and respiratory measures, including VO2max. The authors speculated that the improved performance time for the sauna suit group was due to improved VO2max and increased capacity for thermoregulation. For example, they noted that sweat rate during a heated 5 km time trial increased in the post-intervention group but not the control group (Van de Velde et al. 2017)".
  • I am confused. The summary of this stufy does not even mention "sauna".
  • In any case, I guess the same points about the study above apply. A "sauna suit" most likely implies a very small sample size, and they did not measure mortality.
• "A small intervention study in humans found that daily heat treatments applied locally to muscle during 10 days of immobilization prevented the loss of mitochondrial function, increased HSP levels, and attenuated skeletal muscle atrophy by 37% compared to a sham treatment group (Hafen et al., 2019)". Very weak evidence because:
  • By small, they mean "23 healthy volunteers".
  • They did not study realistic conditions. "This study investigated the effects of daily heat therapy on human skeletal muscle subjected to 10 days of immobilization". The question is whether sauna helps random healthy people longterm, not whether they temporarily benefit people who were spending 10 days without moving.
  • This is not about sauna. It is about local heating. "daily 2-h heat treatment using pulsed shortwave diathermy".
  • They did not measure mortality.

Hi James.

• NPS of 63 (mean recommendation: 8.86/10).

In case anyone is wondering, NPS stands for net promoter score, and is equal "fraction of people giving a score of 9 or 10 (promoters)" - "fraction of people giving a score of 0 to 6 (detractors)".

Hi Ozy.

By looking at this picture, you can see that we’re pretty certain that humans are conscious and very certain that ELIZA is not conscious. We’re uncertain about whether chickens and 2024 LLMs are conscious.

These conclusions only hold for a prior probability of consciousness of 1/6. I think this prior is very arbitrary. So I believe the results for the (posterior) probability of consciousness are also very arbitrary.

We are pretty certain about how uncertain we are about whether 2024 LLMs are conscious (we think there’s about a 10% chance they’re conscious). But we’re not only uncertain about whether chickens are conscious, we’re very uncertain about how uncertain we are about whether chickens are conscious.

The model underestimates the uncertainty of the distributions of the probability of consciousness. The weights of the stances are set to point estimates. However, Figure 7 of the report shows the 13 experts surveyed were very uncertain about the weights. I would set the weights of the stances to very wide distributions to represent the very high model uncertainty.

Hi Aaron. Nice post.

In the golden age of public giving, the EA community spent most of its time thinking about where to give. Now, it's more about finding the right job. That's appropriate; the average person can make a much bigger impact by working than giving.

Do you mean random people in the whole population can have a much greater impact through work than giving? I find this hard to believe. Benjamin Todd thinks “it’s defensible to say that the best of all interventions in an area are about 10 times more effective than [as effective as] the mean, and perhaps as much as 100 times”, which is in agreement with the cost-effectiveness of interventions following a heavy-tailed distribution. If so, jobs were uniformly distributed across interventions, and a person in a random job within an area were 10 % more cost-effective than the 2nd best candidate for their job, them donating 10 % more of their gross salary to the best interventions in the area could have 10 (= 0.1*10/0.1) to 100 (= 0.1*100/0.1) times as much impact through donations as through work. In reality, I assume there are more jobs in less cost-effective interventions, as the best interventions only account for a small fraction of the overall funding. Based on Ben’s numbers, if there are 10 times as many people in jobs as cost-effective as a random one as in the most-effective jobs, a person in a random job within an area who is 10 % more cost-effective than the 2nd best candidate for their job, and donates 10 % more of their gross salary to the best interventions in the area is 100 (= 10*10) to 1.00 k (= 100*10) times as impactful as a person in the same job not donating.

Here's a list of examples.

Nitpick. The link links to your post instead of the appendix.

Hi titotal. A "speck of dust in the eye" is supposed to represent something which decreases welfare very little (considering all effects, including decreasing boredom), thus being very slightly bad, and worth avoiding (all else equal). So one can interpret premise 1 ("mild pain is bad") as "mildly decreasing welfare is bad". I believe the arguments in the post work for an arbitrarily small decrease in welfare. Do you agree?

I meant my future decisions would be the same in reality if I could not gather additional evidence regardless of whether the mass of the 2 identical objects was exactly the same or differed by 10^-6 kg.

Do you think annual human welfare per human-year has increased since 1900? Child mortality decreased 37.3 pp (= 0.41 - 0.037) since then until 2023. If you agree annual human welfare per human-year has increased since 1900, are you confident that similar progress cannot be extented to non-humans? Would you have argued 200 years ago that we are all clueless about how to increase human welfare? I agree research can backfire. However, at least historically, doing research on the sentience of animals, and on how to increase their welfare has mostly been beneficial for the target animals?

For example, the articles make the claim that brains make no clear separation between hardware and software. Okay, that seems to be true. But so what? Why should I believe that a lack of hardware/software distinction is a necessary property for consciousness to arise?

Relatedly, I liked the article The Abstraction Fallacy: Why AI Can Simulate But Not Instantiate Consciousness by Alexander Lerchner, and the reply to it by Shelly Albaum.

Hi Bob and Geoffrey.

• Yes, what we do is very unusual outside of academia—and inside it too. Re: other groups that do global priorities research, the most prominent ones are GPI, PWI, and the cause prio teams at OP.

GPI refers to the Global Priorities Institute, which has meanwhile closed down, PWI to the Population Wellbeing Initiative, and OP to Open Philanthropy, which has meanwhile rebranded to Coefficient Giving.

Thanks for the post, Huw.

He provides some evidence that satisfaction doesn’t correlate with momentary wellbeing. However, the WHR’s own data finds a highly statistically significant correlation between positive affect and life satisfaction on the national level (Tables 8–10; FWIW it’s likely that they don’t find the same for negative affect because linear models don’t find additional explanatory power in intercorrelated variables).

I think Yasha is particularly concerned about comparisons across countries.

But perhaps the biggest problem with the World Happiness Report is that metrics of self-reported life satisfaction don’t seem to correlate particularly well with other kinds of things we clearly care about when we talk about happiness. At a minimum, you would expect the happiest countries in the world to have some of the lowest incidences of adverse mental health outcomes. But it turns out that the residents of the same Scandinavian countries that the press dutifully celebrates for their supposed happiness are especially likely to take antidepressants or even to commit suicide. While Finland and Sweden consistently rank at the top of the happiness league table, for example, both countries have also persistently experienced some of the highest suicide rates in the European Union, ranking in the top five EU countries according to one recent statistic.

Southern European countries have the lowest age-standardised disease burden per capita from self-harm in the Europe, but not the highest life satisfaction.

There correlation between life satisfaction and happiness across countries is positive, but very weak.

Great to know.