bars of soap

The following hypothesis was contributed by Derek H. Page and Hugh Smailes:

Several years ago, Ann Landers raised a provocative question in her column: does soap at the foot of the bed cure night-time leg cramps? The consensus in the medical community is no: there is no conceivable mechanism by which it could, so any relief derived from this procedure must be due to the placebo effect. In other words, it’s all in the mind.

But if it is indeed a placebo effect, it’s a remarkably strong one. Many people who have suffered for months, if not years, from painful, nocturnal cramps in their legs and feet have found immediate and long-lasting relief just by slipping a thin, innocent bar of soap beneath the sheets. Some even report relief although they were unaware that a bar of soap had been snuck into bed.

Likewise, others whose cramps have mysteriously returned have been nonplussed until they later discover that their bars of soap have fallen from the bed. From the point of view of those who, like us, are trying to solve this mystery, it is fortunate that several websites (including this one) have maintained reports of this unusual treatment and its results.

We decided that although these data were anecdotal, and therefore suspect, we would treat them as if they were scientifically valid, and use them to try to develop an explanation for soap’s seemingly helpful effects. But as soon as we started reading the literature, we realized what an enormous task we had undertaken. The anecdotal literature is vast, and frustratingly contradictory.

Nevertheless, we decided to continue, recognizing that any explanation we produced would remain an untested hypothesis. It would require testing by others before it could be elevated to the status of a theory. We decided to condense the relevant literature down to a few points on which there is general agreement. Here are the main relevant observations taken from the anecdotal evidence:

  1. It seems to work for many people. Soap in the bed appears to alleviate nocturnal leg cramps.
  2. Relief is immediate and sustained.
  3. Some people report that soap does not work. It appears either to work consistently and well or not at all. There are few cases of partial success.
  4. After a few months, a bar of soap is no longer effective for preventing cramps. It must be replaced. Old soap can be rejuvenated by scoring or shaving it to produce fresh surfaces.
  5. Some subjects have placed the soap between the sheets, and some have placed it under the bottom sheet. Either or both of these methods work.
  6. Some subjects report that direct physical contact between the subject and the soap is desirable, but few claim it is essential.

From these observations, certain conclusions may be drawn. For our purposes, number 4 on the above list is the most relevant. Apparently, the phenomenon can be switched off and on: off when the soap bar ages, and on again by scoring the soap. But why? What is it that’s being switched off and on? We hypothesize that it is an as-yet-unidentified molecule present in the soap. This might sound like a stretch, but in fact, this “switching” mechanism is consistent with what we know about the structure of soap.

Soap is a water-swollen gel. When it’s purchased, its moisture content is generally somewhere between 5 to 15 percent. Soap is very porous, and when it’s swollen with water, it permits small, dispersed molecules to pass through it. But when it has aged, its surface dries out, and its surface is a lot less porous, so small molecules can no longer pass through it.

We think that an unknown molecule that diffuses out of the soap gel is responsible for alleviating cramps. As long as the bar is emitting this molecule, the cramps are suppressed. An old bar of soap ceases to emit the molecule as the surface dries out and its resistance to diffusion rises. That’s when the cramps return. The bar can emit again–and once again eliminate cramps–after new, moister, fresher surfaces are exposed by scraping the bar of soap.

From items number 5 and 6 from our list above, we know that direct contact between soap and skin can be helpful, but it does not seem to be essential. This suggests that our unknown molecule is volatile, capable of diffusing in air: i.e., that it can pass from a bar of soap to your cramping leg in a manner similar to the way a drug is transmitted through a skin patch.

After generating this hypothesis, we took a careful look at the list of ingredients on a package of soap, and we found only one possible source of small molecules of a volatile compound: the fragrance. Nearly all soaps contain fragrances or perfumes. Certainly those mentioned in the anecdotal evidence do. And what perfumes are used in soaps? That’s generally top-secret information, held close to the vest by soap manufacturers. But we do know that most soaps contain esters and oils, such as carrot oil and lavender oil (or their synthetic doppelgangers). These compounds are vasodilators.Like the ester nitroglycerin, which is used to alleviate pain caused by angina, they enlarge blood vessels.

The quantity of perfume transmitted to the skin may be small, but it appears to be enough to dilate blood vessels and prevent cramps. We know, of course, that the small, mobile molecules in the fragrances of soap diffuse through its gel to the surface and evaporate. We know because we can smell them. And when you score an old bar of soap, you can smell it all over again, just as strongly as when you first took it from its paper wrapper.

Before it can be accepted, every new hypothesis has to be tested. We would welcome the findings of anyone who might want to test our hypothesis, and we would be eager to see the results. To the research community, which is convinced that ion imbalance is responsible for the initiation of cramps, we say that this suggestion doesn’t challenge that. There is ample room here for research by the academic and medical communities. Our proposed mechanism will surely be under attack within the week. Yet it fits much of the data so well that we suspect that whatever future research results are obtained the final conclusion in this matter will include much of what is written here.

Finally, it has not escaped our notice that if this explanation is correct, it may have applications beyond the alleviation of leg cramps–specifically, but not only, in the management of pain from other conditions. We hope that having proposed this scientifically viable explanation for the phenomenon of soap alleviating leg cramps will validate the experiences of those that have benefitted from this “treatment,” and open this area of inquiry to further medical and academic research. We do not claim originality for every element of this proposal. But we do claim originality for putting together the pieces of this puzzle.

To those who have been unable to get relief with the soap treatment (i.e., those mentioned in item 3 Above), we suggest you persevere and try a different soap with a stronger scent, potentially scoring it. You might try searching the internet, or this website, to see if there’s a brand others have had good luck with. The fresh, unwrapped bar of soap should then be placed between the sheets, preferably in a location where the soles of your feet can touch it. And please report back to us whether or not it works–we’d be very interested to hear.


Dr. Derek H. Page, (Baie D’Urfe, Quebec, Canada) and Hugh Smailes (Apollo Bay, Victoria, Australia) As a final disclaimer: we are not physicians and have no health expertise, as our critics will doubtless be happy to affirm.

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  1. Michelle
    Indianapolis
    Reply

    This definitely works! I don’t care how or why, but it does. I would get cramps from my feet up to my inner thighs and could barely walk. Slam, bam, bar of soap, no more cramps. Who’d thought? I don’t care how hokey he looks or sounds. Better than taking a pill, like the pharmaceutical companies would like.

  2. Gina
    Green Bay, WI
    Reply

    I don’t know how this works, but it does work! I am curious why scented lotion wouldn’t work. Or even fabric sheets. There must be more to it than just the scent.

  3. Becky
    Virginia
    Reply

    My theory is that people with restless legs and leg cramps often generate a lot of static electricity by moving their legs against the sheets and blankets (try looking under the covers when you are wearing flannel pjs and moving your legs around in the Winter, and you can see the sparks shooting around). The soap in some way grounds the electrical charges, so the static “zings” that these people are feeling unconsciously in their sleep no longer cause their legs to react and move around to avoid the minute electrical charge. This isn’t really based on any particular science, but as an acupuncturist, I believe that very tiny pizoelectric charges can have a big effect on the body….what does anyone think about this idea?

  4. Annette
    Arizona
    Reply

    I opened the bar of soap and removed the wrapper. May have to change it more often by worth it!

  5. Virginia
    Central New York
    Reply

    I am amazed that a bar of soap placed under my bed sheet actually relieved my night time leg cramps.

  6. Virginia
    Louisiana
    Reply

    I read on Facebook that placing a bar of soap between the mattress and the bottom sheet would alleviate leg cramps. I tried it several nights ago and no leg cramps! I am convinced it works I have suffered terribly especially since being placed on a cholesterol reducing medicine. I will continue to use it, grateful I found it.

  7. bellabecka
    VA
    Reply

    If you have a charlie horse in your leg or in your foot, try flexing your foot up towards you and hold it there till the pain subsides. I do this everytime I get one and it works every time whether sitting up or laying down.

    • Gina
      Green Bay, WI
      Reply

      Yes, my aunt was a nurse and she taught me that. It does work very well and every time. :-)

    • emily
      Austin
      Reply

      Yes, until the shin muscle cramps up. I get them all of the time and it takes walking around for several minutes to help. I’ll try the soap. It can’t hurt.

  8. Michelle
    Kansas
    Reply

    If it is about the fragrance, then wouldn’t a scented lotion do as much?

  9. Barbara
    Virginia
    Reply

    It works!!

  10. Klári
    Hungary
    Reply

    It is always the simple and natural solutions to problems that seem to work the best. And sometimes the solution is quite incredible but hey if it works? Great! I am going ot try it I just have to buy a bar of soap because I use liquid soap to wash my hands.

  11. Wons
    Arkansas
    Reply

    If this is true then wouldn’t essential oils work? Or would it have more to do with the gradual release of the scent?

  12. Tab
    Bluefield, VA
    Reply

    I’m sure that if you used a lavender, peppermint, or chamomile specific soap, it would work even better!

  13. Sharon
    Illinois
    Reply

    I am watching great Grandma at 104 yrs old this weekend at my mother-in-law’s home and after thinking my foot hit a dog toy in the bed the night before I asked my husband the next morning to see what is under the covers at the foot of the bed …..

    OMG a bar of soap, the irony of the story is, I never heard of this but I have terrible foot and leg trouble and he was laughing when I told him I had no trouble hopping out of bed pain free!

    Honestly had I known prior I would have not believed it. I had no idea it was there or the story behind it, I will be putting a bar of Irish spring in my bed when I return home!!!! Placebo effect or not???????

  14. Jean
    Reply

    I’ve been using it for about one month and no more leg cramps. I’m glad I read the article so that I know to switch to a new bar every couple months. An added bonus the tingling in my feet seems to be subsiding.

  15. dale
    Florida
    Reply

    I had read of this in several different articles. I read it tongue in cheek and thought how stupid is that? Last week my sleep was disturbed AGAIN by leg and foot cramps and I leaped out of bed to walk them off. I was so annoyed at this sleep interruption. Out of nowhere the soap remedy popped into my head and I went and got a fresh bar of soap and put it at my feet under the sheets. I had nothing to lose, not even my dignity. I haven’t had a leg or foot cramp since I put the soap in my bed! Who knew? It did work for me.

  16. Marcia
    Maryland
    Reply

    It works! I tried this “solution” this past weekend and I was able to sleep for the first time in weeks! Whether the bar of soap is actually a cure, who cares, it works!

  17. Leonard
    tennessee
    Reply

    I was having leg pain for several days. I took hydrocodone and it helped but it would come back.. A lady told me about using soap under the sheet. After two nights the pain was gone and it has not come back.

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