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. Bill
    uk
    Reply

    I read the article about soap is a cure for cramps, and as i have suffered from feet and calf cramps at night, and may i add so bad i do have to get up until i can get rid of it. If i’m honest i don’t normally take any notice of some of these old wive’s tales, but it was disturbing my sleep almost every other night.and i used to take Crampexe but they have stopped making the product until 2017 so the company tells me. So i put a bar of soap under the bottom sheet and on top of the mattress, and low and behold it has worked. I have started to feel cramp starting a few times and whether it was right or wrong i put my foot or my calf on the bar of soap, and i cannot explain but my cramp just disappeared. I have been using soap for 2 weeks now and have not had to get out of bed at all and havn’t had cramp bad. All i can say is it worked for me and i havn’t got an answer to it.

  2. Laura
    San Antonio, Texas
    Reply

    I heard about this from friends. I thought what harm could come from trying this! I used a new bar of oil of Olay soap and immediately my every night cramps and pain stopped. What’re the reasoning it works and has continued to work for the past 9 months!! Try it ! It may work for you! ⭐️✨🌟

  3. kathy
    kokomo, in
    Reply

    Ive been doing this for about 2 months..its working for me!! I use Dove soap..the pink one 😁

  4. doreen
    Williams Bay Wisconsin
    Reply

    It would be helpful to know if all bar soap works, or if it must contain specific ingredients beyond fragrance.

    • Bill
      Reply

      Hi, i just used an ordinary bar of soap from the bathroom.

  5. sue
    mayflower ar
    Reply

    I use my homemade soap for leg cramps. I put a fresh bar between my sheets and wow no leg cramps or restless leg cramps.

  6. Walter
    South Carolina
    Reply

    When I turned 64 I had to have both ankles replaced due to cartilage loss. I had been unable to walk much for the previous three years so both calves had lost most of their size and muscle. A year after the ankle replacements I started experiencing leg, foot and toe cramps in the early hours. Over the next two years the cramps became increasingly worse. My family doctor told me to eat an orange each day to add potassium but didn’t help, she referred me to a foot doctor who told me it was just getting old. Someone suggest putting a bar of soap under the sheet which my wife did and I haven’t experienced any cramps for two nights now, fingers crossed. The only other change was I stopped taking a D3 2,000 vitamin .

  7. Phil
    Sydney, Australia
    Reply

    My wife (60+ years of age) has suffered from leg cramps at night for years. When we first heard about a bar of soap in the bed being a possible cure for cramps we were doubtful but decided to give it a try since nothing else had worked. And we were astonished to find that adding a bar of soap or two to her side of the bed has actually worked!
    It’s not 100% effective but it’s scoring at least 90% with her after six months and that’s amazing. Even more impressive is the research that’s been done and concluded much the same as we have: there’s no apparent reason for it but it just works.
    My wife’s explanation, by the way, is that while sleeping she moves her feet around to ‘find’ the soap and that little bit of exercise and stretching during the night stops cramps from building up. Whatever the reason, we can happily recommend a bar of soap in bed for anyone experiencing night cramps in their lower extremities. It doesn’t cost much and it’s helped both of us get a better nights’ sleep for the past six months.

  8. Stuart
    Brisbane
    Reply

    My daughter, who gets woken with leg cramps most nights, just tried this on the insistence of her grandmother. No leg cramps, or even a hint of them, the first night. I was pretty sceptical and called this an old wives tale. I may have to apologise to my mother-in-law!

  9. Louis
    Florida
    Reply

    Works for me. I inhale the soap when a cramp appears and the cramp goes away.

  10. Kim
    GA
    Reply

    I have suffered for years, probably due to dehydration and mineral deficiencies. I had read about it for years, but was reluctant to try it until an elderly aunt swore she had had relief for years. So, in the 3 weeks since I started using soap at the foot of my bed, I have not been woken once with a cramp. In fact, you know that weird tingly feel you get just before a cramp hits? I can touch the soap when I feel that and it immediately stops. I use the fancy Irish Spring exfoliating soap only because that’s what I had on hand.

  11. Loraine Findlay
    Stone Hut, South Australia
    Reply

    Ì tried soap but didn’t work for me. Everyone’s makeup is different I suppose. A friend suggested putting a cork from a wine bottle in bed, has to be real cork and I have found that it works. Have been using cork now for about 6-8 weeks and no more night cramps. It’s fantastic. I can now sleep all night.

  12. Michael
    Rosemead, CA
    Reply

    My wife uses it and it works for her. She also uses soap if she gets a cramp while awake while walking or just sitting. She carries a little bar like what you may find in a hotel or given as a sample and rubs it on her leg. Cramps start to go away immediately.

  13. dianne
    Reply

    What brand soaps can I try for severe leg cramps? The brand would be helpful!

  14. Marten
    Ireland
    Reply

    Legs cramps?

    This is because if a person has too many blankets on the bed, air cannot circulate. What happens then is a chemical builds up in ones legs giving severe cramps. I used to get this back in 1979 and since I changed bedclothes to lighter duvet, I never got them again.

    • K
      Reply

      That’s not always the case. Even during our harsh Wisconsin winters I sleep with only a flat sheet covering me because I get too warm.
      I have unspecified leg tremors coupled with Restless Leg Syndrome.
      The tremors cause cramps sometimes. Other times my legs give out completely and I collapse.
      The Restless Leg Syndrome gives the oddest sensations in my legs and feet to the point I feel the need to kick them around like I’m running in bed.

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