On my radio show today the story of putting a bar of soap under the sheet to cure leg cramps came up again. When science leaves a void, as it does with the treatment of leg cramps, unconventional therapies rush in to fill it. Just take a bar of soap, some say it has to be Ivory, place it on the mattress under the sheet and ...pleasant dreams! There are testimonials galore from people who say they thought it was a ridiculous notion, but they decided to try it anyway out of desperation, and it worked! Anecdotes are scientifically meaningless, and the plural of anecdote is not data. Scientific validity can only be ascertained by randomized, controlled double blind trials. None such have been carried out on the soap question. Why not? Because such trials are difficult and expensive to carry out, and to justify mounting one, there has to be some plausibility of a meaningful outcome.
Aside from far-fetched ideas about subliminal scents, there is no conceivable way that a bar of soap under the sheets can have an effect on leg cramps. It is possible that some people who have struggled long and hard with such cramps want so much to believe that something will help, that they will respond to the presence of the soap. That's what we call the placebo effect. Of course if the sufferer feels better, it doesn't much matter why. I suppose there is no harm in telling a sufferer that "some people believe the soap helps" and suggest they give it a shot. That little white lie doesn't break the number one rule of medicine: "first of all, do no harm." It is hard to imagine how a bar of soap might do harm, although I suppose there is a chance it can drop to the floor due to the motion generated by a leg cramp attack and cause someone to slip on it.聽
