Sweat Intuition

I sweat, a lot, though I’ve never thought asked a doc about it. So why is it that I’ve just learned this?

So-called clinical-strength antiperspirants …come with instructions that they be applied before bed for “maximum” protection from wetness and odor. … Even regular-strength antiperspirants work best when applied to underarms at night, experts told us.  Bedtime application “really is the best way to use an antiperspirant,” says Daivd Pariser, M.D., president of the American Academy of Dermatology.

At night, when people perspire less, more of the antiperspirant’s aluminum-based active ingredient is pulled into the sweat ducts. Because there’s more antiperspirant present, it more effectively plugs pores.  That signals the sweat glands to reduce or stop perspiration.  the effect lasts 24 hours or possibly longer, even after morning bathing.  Eventually, the antiperspirant washes away.  Blocking perspiration by plugging pores might sound unhealthful, but it’s not, medical experts we consulted say.

That is the July Consumer Reports, p.12. Other sources agree. Now surely experts have known this for a long time; why isn’t the word out?

When I told my wife that Consumer Reports said antiperspirants should be applied at night, she said that was just silly, and was not persuaded.  And folks commenting on clinical-strength antiperspirants are often skeptical:

The product is very easy to use, but does have some strange directions that are unlike normal antiperspirant products.  First, you’re supposed to apply it at night before bed … I did not use it at night, only after getting out of the shower.

Do the rest of you also see resistance to this advice?  Why do people think they are such experts on the right time of day to apply antiperspirant, so that they prefer their own intuition to Consumer Reports, doctors, and manufacturer’s directions for use?

Added 4June: Many say what is the point if you already feel dry enough?  But there may be a real health risk from common dosages; if using it at night is more effective, then you can reduce the dosage and still get an acceptable effect.

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  • Pingback: Who Knew? Sweating is the pits.

  • http://michaelkenny.blogspot.com Mike Kenny

    Low and high openness might lead to accepting or shooting down a novel idea respectively, without much thought. Low conscientiousness might lead to not following instructions, and low agreeableness might cause one to interpret directions cynically and discount them.

    So maybe we’re just executing strategies that are kind of ingrained in us and have been tried and true and emerge as personality, and we have a little wiggle room perhaps, but not too much.

  • Phil

    You’d think if the label explained why you’re supposed to put it on at night the way Consumer Reports did, people would be more willing to accept the instructions.

    Um, Robin, was your wife dismissive of your explanation, or of the Consumer Reports explanation? Because “Consumer Reports says to put it on at night” wouldn’t convince me either. I’d need an explanation of why that works better.

  • ES

    I suspect most people are little concerned about maximizing the effectiveness of their antiperspirant, and more concerned about being considered normal. Optimizing minor habits like this demonstrates a nerdy obliviousness to social norms.

  • Ben Leslie

    I would have thought that having the explanation of why you should put it on at night, not at other times would aid in convincing people. Of course, this does not actually answer your question, since people don’t really need to know how other things work in order to follow ‘experts’ advice.

    I would guess that people have an (intuitive) model in mind of how it does work, and in these cases they need an explanation, not just an assertion.

  • http://delibertate.com Robert S. Porter

    I might agree with you, ES, if putting on anti-perspirant were a public act. However, virtually no one, aside from a partner, would know when it was applied.

  • NE1

    In line with the study on xeroxing and cutting line, where any excuse will do, maybe?

  • http://federalism.typepad.com Mike

    Because “Consumer Reports says to put it on at night” wouldn’t convince me either.

    Yet that is the point of Hanson’s post! Why do you think your intuitive sense of proper antiperspirants application is superior to people who have presumably studied the issue?

    Sure, a person can say: “Hanson is appealing to authority here.” Fine. That doesn’t end the discussion.

    Why do you think your intuition about something you have never studied is a superior authority?

    If I have to follow two courses of conduct: One based on my (ignorant) intuition; and one based on experts: I’m going to listen to the experts.

    If, after extensive independent research, I conclude that the experts are wrong, then I will do what I conclude is proper.

    See the difference?

    Here, people who have never thought about the issue are saying, “Well, the experts really need to present a mountain of evidence to get me to change my habits…. which, after all, are based on nothing more than what seems to make sense to me…. which is based on no independent study or research at all.”

    I do not espouse taking what experts say on faith. Again, though, I would think that it’d be up to me to prove why the experts are wrong. Instead, people with nothing more than intuitions are placing the burden of proof on the experts!

    That’s fascinating to me.

  • http://simply3d.wordpress.com Andy Wood

    Simple in my case. I’ve never seen the suggestion before, much less the explanation. Without the explanation, I’d assume the product would not work after my morning shower. Even with the explanation, it goes against common sense (“products wash off”), but I’d be willing to try it.

  • http://blog.greenideas.com botogol

    It’s a good question. I observed exactly the same phenomenon skiing a couple of years ago: in a beginners’ lesson many times I saw skiers listen carefully to the instructor’s directions, and then ignore them becasue it didn’t seem right. ‘yes, well I find it easier to….’

    same thing: why pay for lessons from an expert, but then discard any instructions that go against one’s intuition?

  • http://liberalvichy.blogspot.com/ Vichy

    “I suspect most people are little concerned about maximizing the effectiveness of their antiperspirant, and more concerned about being considered normal.”
    One thing I have found in myself and some others diagnosed with Asperger’s syndrome is that the very inverse tends to be true – for example, it took me years to figure out why relatives tried to by me stupid gifts when, knowing I was an intellectual, they could not have plausibly known what I would actually enjoy – giving me money was far more practical. Likewise with things like romantic relationships, the way men will pretend they aren’t primarily interested (at least initially) in sexual advancement even though both parties are certain of it.

  • http://www.churchofrationality.blogspot.com LemmusLemmus

    Because people are taught from an early age onwards that critical thinking is a good thing – and then overdo it? In this context, I think people differentiate too little between experts who have an interest to mislead you (car mechanics), those who have an interest to tell the truth (Consumer Reports) and those who are neutral in this respect.

    Also, if you act on the basis of your intuition, you’re in control; if you act on the basis of someone else’s work which is a black box for you, you give up control.

  • Dusty

    Perhaps most people are content with their current level of antiperspirant effectiveness and changing their morning and bedtime routines is more effort than any possible gains could justify. My deodorant works fine when I put it on on the morning, so there is no reason to change.

    If Consumer Reports published a study saying that pumping gas between 10pm and midnight will increase your fuel economy by 10%, I think more people would be receptive to make the change.

  • Phil

    “Yet that is the point of Hanson’s post! Why do you think your intuitive sense of proper antiperspirants application is superior to people who have presumably studied the issue?”

    Good question.

    Perhaps my problem is that I don’t consider Consumer Reports all that reliable on these kinds of issues. (Which is true.)

    Perhaps I might think that the authority’s reasons don’t apply to me (“put it on at night so you won’t forget in the morning.”). There is ample precedent for that kind of thing (aren’t there a bunch of placebo pills in a month’s worth of birth control?).

    Maybe I don’t think that Consumer Reports has actually studied the issue, and maybe I suspect they’re just echoing the manufacturer (for testing, they follow the manufacturer’s instructions exactly). Of course, that begs the question of why I might not trust the manufacturer.

    Finally, maybe I think that the advantage of putting the stuff on at night might not outweigh the disadvantages of having to sleep with it on. There are lots of little health tips that are a pain in the butt for very little benefit. Everyone tells me I should eat brown bread instead of white … but I don’t like it. Should I really eat something I don’t like just to add an expected five minutes to my lifespan? Similarly, should I disrupt my normal bedtime routine of the antiperspirant is only going to work 1% better?

  • http://silasx.blogspot.com Silas Barta

    Per Andy_Wood, the CR claim butts up against a very strong prior of mine: specifically, that rigorously scrubbing my armpits with soap during my morning shower should effectively delete any remaining epidermic chemical effect of the deodorant/antiperspirant.

    Even if they modified the claim to “put it on at night, but don’t scrub your armpits during your shower”, I still have good reason to be skeptical. Showering simulates a high sweat environment and I know that that’s enough to destroy the effect of deodorant. Morever, I sweat a lot more than most people, even when I’m not tired, and my deodorant usually loses its effect by mid-day, and I occasionally sweat at night.

    If my sweating levels were lower, and I didn’t shower in the morning, I’d definitely give this idea a try.

    Now, tell me: how unreasonably biased am I?

  • http://federalism.typepad.com Mike

    Phil: Your entire response presupposes that you have something useful or interesting to say about an issue you never studied. That seems to me, again, to be what Hanson was getting at. Why do you think your opinion, which is an intuition, is relevant to the discussion?

    Why do people who have never studied an issue believe that their opinion has any validity – yet alone enough validity such that experts should have to make a compelling case to persuade the ignorant to change their habits.

    There is a nuance I often see missed by commenters at this site. People seem to think, “Well, experts are always wrong. Therefore, my opinion is as good as any experts!”

    It’s true that one need not blindly follow experts. One should indeed research evidence, and think critically. Yet it does not follow from those statements that any view is as good as an expert’s view.

    No offense, but your view on antiperspirant usage is worthless. As is mine. Our opinions are not based on anything other than, “Hey, my arm pits are clean after a show. So now seems like a good time to put the stuff on.”

    Basically, you’re saying, “This is how I do it and have always done it. I have put no thought into why I do this or why it should be the right way to do it. I’ve never read a book – let alone magazine article – on the right way to do this. Still, my opinion is as valid as any experts.”

    So, again: Why do people with no formal or informal knowledge of a subject think their opinions are entitled to any consideration at all – let alone whether their opinions are entitled to greater weight than an experts?

  • Mr. Econotarian

    Perhaps this is due to the difference between optimal use time of deodorant vs. anti-perspirant.

  • Constant

    No offense, but your view on antiperspirant usage is worthless.

    Not true. The world is not a bazillion utterly disconnected facts. The world is well-connected. Therefore a person’s opinion on a new question is not worthless. It has some positive value.

    People encounter novel situations every day. They apply general knowledge – generalizations from past situations if you like – to the novel situations. Often enough, they are right.

    Why do you think your opinion, which is an intuition, is relevant to the discussion?

    You know, I think that before people use the word “intuition” they define what they mean. Frankly, on your current apparent definition of “intuition” (as a near-synonym for “worthless”), a typical person’s opinion on deodorant use is not an intuition. A typical person who uses underarm deodorant has potentially years of experience with its use. This counts for something. Now, in the current case that experience appears to leave a critical gap through which the truth can slip, but that is not always the case. You don’t know a priori that in any given case a person’s years of experience have let the truth slip through the cracks. It may – in this particular case it apparently has – but it doesn’t necessarily, and it would be irrational to assign a zero value to it.

    Why do people who have never studied an issue believe that their opinion has any validity – yet alone enough validity such that experts should have to make a compelling case to persuade the ignorant to change their habits.

    Who says the people at Consumer Reports are “experts”? How do you know they’re experts? Consumer Reports are reviewers, and the main value of a reviewer is that he is somebody who has tried the product, so you don’t have to go to the expense and bother of it. It is not required that he be an “expert” in anything, and so Consumer Reports is valuable to me without me having to assume that they are “experts”.

    Finally, you are completely ignoring Phil’s last point:

    maybe I think that the advantage of putting the stuff on at night might not outweigh the disadvantages of having to sleep with it on

    Even if someone is an expert on underarm deodorant, they are not an expert on Phil. Phil is the best expert on Phil. And any recommendation is necessarily a combination of information about the deodorant and information about Phil. So the experts’ recommendation may be wrong – on account of them not being experts on Phil.

  • Drucker

    I think people don’t consider deodorants a medical, but cosmetic good. Its used like cologne, so naturally it should be applied after you’ve cleaned yourself and nearest to when you’ll be presenting yourself to society. For cosmetic uses I don’t think I’d ever need to consider a medical opinion.

    If you are a heavy perspirer you are more likely to actually need the active ingredient of the antiperspirant to maintain normal perspiration levels, so you may be more open to advice from experts, but the majority of people using the good for cosmetic purposes leads to a misleading common sense prescription.

  • David Rotor

    While you are investigating the optimal application strategy, you may also want to have a look at the research around aluminum levels in the brain and alzheimer’s disease.

    At this time the evidence seems non-conclusive, but given the low cost of avoiding products that apply aluminum directly to the skin (many deoderant brands use aluminum), it seems an easy choice to make.

  • http://wiredcola.com Ryan Cousineau

    Wait, am I the only one here who immediately thought “that’s an interesting theory! I will try that out!”?

    Because rather than argue about this, it’s an incredibly easy thing to test, with the only test subject any of us really care about (ourselves) and with almost no costs.

    So yeah, I think I will do an experiment with using an expert-recommended protocol for deodorant application and see how well it works.

  • http://www.greenecg-llc.com Carrie Cooper

    That’s funny, I’ve always applied at night. Not only does it keep me that much dryer, but it also doesn’t rub off on my black/dark colored shirts in the morning as easily.

    Also, the clinical-strength variety can stain some types of fabrics so it’s definitely better to apply at night.

    As for why people don’t do or know this trick, I bet it’s a competition thing. I’ll look that much better if I’m dry and sweet-smelling while you’re stinky with pit stains.

  • http://federalism.typeapd.com Mike

    Even if someone is an expert on underarm deodorant, they are not an expert on Phil. Phil is the best expert on Phil. And any recommendation is necessarily a combination of information about the deodorant and information about Phil. So the experts’ recommendation may be wrong – on account of them not being experts on Phil.

    This is still question begging. How did Phil become an expert on how Phil should use antiperspirant? From using it improperly for several decades?

    Moreover, how expert are people of themselves? Decades of research on cognitive bias show that people get things wrong about themselves on even important facts. People think they are more skilled, better looking, and more intelligent than they actually are.

    Indeed, this blog’s focus in on overcoming the bias that we have about our world and ourselves.

    So it might be the case that Phil is most certainly not an expert on Phil. Just as you might not be an expert on yourself; and just as I might not be an expert on myself. We could all be confused or deluded.

    Who says the people at Consumer Reports are “experts”?

    This is the type of weak critique that I noted in an earlier comment.

    There’s a line between, “Be skeptical of experts,” and what you suggest. You can’t just throw around, “Who are they to tell me anything,” in a vacuum.

    Yes, there are indeed expert sources of information. Snopes, e.g., is considered an expert resource for a reason. They get things right, over and over again. For the same reason, Consumer Reports is considered an expert source.

    If you want to suggest that CR is incredible, then the burden of proof is upon you to discredit them. It’s not the other way around.

  • Alex

    When I was younger I applied deodorant before going to bed. My mother found me doing that and told me to stop. Her justification was that deodorant clogs the pores AND causes more pimples. Being a vain teenager, I heeded her warning.

    Just my story, don’t know how common it is.

  • http://www.zianet.com/ehusman/weblog/blogger.html Eric H

    If recent experience is anything to go by, Consumer Reports has largely become a political advocacy group that maintains a truthy, sciency facade to give their advocacy more credibility. Experts? At the political process, perhaps. I’m specifically referencing their recent forays in the form of the Consumer Product Safety Improvement Act and recent reviews of baby carriers.

  • Phil

    Mike: it is true that I know nothing about antiperspirant use. And it is also true that I am willing to take expert advice on how to use it, even if that contradicts my intuition.

    But “Consumer Reports says to put it on at night” is not enough to convince me that I’m hearing expert advice. And it’s not enough to convince me that, even if it is better to put it on at night, the benefits outweigh the costs.

    So when you say, “your entire response presupposes that you have something useful or interesting to say about an issue you never studied,” I say, first, that I have a certain amount of experience with antiperspirants (as Constant notes above). And your argument is weak — you just haven’t given me enough information by “Consumer Reports says to put it on at night” to counter my instinct and preference to put it on in the morning.

    If I read “it’s 50% better to put it on at night” in a reputable textbook on perspiration technology, things would be different.

  • rob

    this is a bit of a non sequitor, but i wanted to share a huge lesson i learned on deodorant vs antiperspirant.

    for some medium to heavy sweaters such as me and several of my close friends, antipersp actually led to heavier sweating and pitting out of shirts. our theory is that the antipersp blocks the sweat glands, causing the body to overheat and eventually leading to very heavy sweating that overwhelms the antipersp.

    as counterintuitive as it sounds, i and several others i know enjoyed far less sweating/pitting once we switched to straight deoderant. while out theory of why it happens may not be right, the results are clear.

  • Shane M

    Because my hairy pits tend to stink in the morning regardless of whether they’ve got deodorant on them or not. After a shower and scrubbing – yes with a scrub brush – I smell much better. A new application of deodorant seems to keep me from sweating throughout the rest of the day. Seems to work for me.

  • Tom West

    Re: People ignoring instruction that contradict their own mental model.

    One of the most valuable things I learned in university about software documentation is that if you don’t provide some sort of mental framework for your instructions, people will very quickly create their own. Even better, when your instructions then contradict the mental model they’ve constructed, they’ll ignore your instructions over what their model tells them is correct. Thus it’s always dangerous to simply provide a “do this” list without adding “why you’re doing this”.

    (Of course, if your instructions are too long, they’ll just ignore them entirely, so you can’t win that way either :-))

  • http://hanson.gmu.edu Robin Hanson

    I removed a 650 word comment by Tracy. See the About page for comment policy.

  • Ian

    Robin, why not restrict comment length using something like Greg’s Comment Length Limiter? Long comments are almost invariably poorly thought through, so maybe this would result in better comments.

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  • Tracy W

    Sorry for missing the word limit rule. I’ll try a shorter one.
    There is a difference between saying that you’re an expert, and actually being an expert. What incentive did the researchers into the timing of deodorant application have to get their experiments right? Many “experts” in the past have given advice that has later on been drastically changed, eg should babies be fed on demand, or strictly every 4 hours? What illnesses should bleeding be used for? Should we eat a high-protein, or a high-carbohydrate, or a high-complex-carbohydrate diet?
    It strikes me that in those cases where “expert” advice has most changed are ones where experts have limited incentives to be right. I would trust a mountaineer’s advice on mountaineering ropes, they literally lay their life on the line. I would trust an engineer who builds working cellphones as an expert on cellphones, if your cellphone doesn’t work it’s obvious. I trust smoking research because tobacco companies have ample incentives to criticise it, keeping the researchers on their toes. But I don’t see that deodorant manufacturers have a strong financial incentive to criticise any studies into the timing of deodorant application, and doctors treat too wide a range of diseases to spend vast amounts of time on sweaty armpits. Nor has any doctor I know ever mentioned spending days following what happens to people’s pores. It therefore strikes me that it is quite possible that the studies have never been thoroughly critically examined, and therefore that there are quite possibly a myriad of errors in the research. In these sorts of cases, a certain skepticism about claims of expertise strike me as wise, given the past failures of experts.
    And Consumer Reports apparently only reports what doctors and manufacturers say, they don’t appear to have done any critical research into it themselves. Furthermore, they’re talking about the timing of application, not whether the product itself is any good, so it seems unlikely that they would be sued by the manufacturers if they get it wrong. So why should they be regarded as experts on this topic?
    I’ll try the deodorant on at night, out of my own interest and because the experiment is cheap. I predict I won’t see a noticeable difference because of natural variations in the weather and the amount of exercise I get.

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  • Tony

    People won’t change because what they are doing is working.

    While, as stated, there are habits and cultural reinforcements; “good enough” is completely satisfactory. If it didn’t work then people would fin other solutions.

  • http://fashion-incubator.com/ Eric H’s wife

    Yeah, ditto what Eric said. Consumer Reports has increasingly stuck their noses into politicking -to their detriment- and ended up with poo stuck to their heels. The whole CPSIA matter has been highly educational. I will never assume an objective consumer interest organization is anything of the sort.

  • Zac Gochenour

    Eric H (and wife), are you suggesting that the recommendation for the timing of deodorant application has some political motivation behind it?

    I agree with commenter Tony. The reason why people are resistant to this advice is that what they are doing is already working. If deodorant didn’t work for someone and you said “I read in Consumer Reports that doctors suggest you put it on at night” I think they’d be more receptive. They perhaps wrongly think that what is being suggested by “putting it on the night before works better” is “putting it on in the morning does not work,” which they know to be false.

  • Elsa

    2 things –

    First, definitely agree this insight is going to be much more resonant with someone more concerned about elevating their level of protection – so, people who have trouble finding effective protection as someone mentioned above, or very type A folk.

    Second, resistance to the idea of putting it on at night, over the perspiration of the day – even if you aren’t particularly grimy before bed (say you shower in the morning) – seems like a psychological hurdle that remains unaddressed.

  • http://hanson.gmu.edu Robin Hanson

    I just added to this post.

  • http://wiredcola.com Ryan Cousineau

    BTW, a quick follow-up: in my recent n=1 experiment, applying deodorant at night seems at least as effective as applying it in the morning, and more effective than applying it right after a shower.

    Not especially scientific, mind: I didn’t blind the test, I haven’t kept a log, and I haven’t been rigorous in A-B testing from day to day to pair up conditions in any reasonable way.

    But I think I stink a little less.

  • gwern0

     The overnight thing, incidentally, seems to go right back to the beginning of deodorants:

    > Although the product stopped sweat for up to three
    days—longer-lasting than modern day antiperspirants—the Odorono’s active
    ingredient, aluminum chloride, had to be suspended in acid to remain
    effective. (This was the case for all early antiperspirants; it would
    take a few decades before chemists came up with a formulation that
    didn’t require an acid suspension.) The acid solution meant Odorono could irritate sensitive armpit skin
    and damage clothing. Adding insult to injury, the antiperspirant was
    also red-colored, so it could also stain clothing—if the acid didn’t eat
    right through it first. According to company records, customers
    complained that the product caused burning and inflammation in armpits
    and that it ruined many a fancy outfit, including one woman’s wedding dress. To avoid these problems, Odorono customers were advised to avoid
    shaving prior to use and to swab the product into armpits before bed,
    allowing time for the antiperspirant to dry thoroughly.http://www.smithsonianmag.com/history-archaeology/How-Advertisers-Convinced-Americans-They-Smelled-Bad-164779646.html