If you suffer from leg cramps that wake you up at night, you’ve no doubt sought some way to prevent them. Some people have been advised to take minerals such as magnesium or potassium to ward off leg cramps, and that may help. Others advocate stretching the calf muscles before retiring, and there is no harm in that. We also hear from many readers that a seemingly silly remedy works: a bar of soap in bed to keep leg cramps at bay.
How Do You Use Soap in Bed?
Q. I read your article about preventing leg cramps with a bar of soap under your bottom sheet. I am a cyclist and often suffer from leg cramps in bed.
I would like to know the specifics of the possible soap solution. Do you just slide a new bar of soap under your bottom sheet? Does it matter what type of soap?
A. What we hear from readers is that a wide range of soaps will work for this remedy. Apparently, French grandmothers have advocated this approach for decades if not longer.
To try it, unwrap a bar of soap. We think some sort of scent in the soap is essential for this remedy to work. Place the bar under your bottom sheet near where your legs will rest. When it stops working, either replace it or score the surface to help it continue to release scent.
Why Does Soap in Bed Help?
Limonene is a common component of some of the oils that are used to provide fragrance in soap. Studies show that it has “spasmolytic” activity–inhibiting muscle spasms–though this has been demonstrated mostly in smooth muscle like the airways and blood vessels of experimental animals (de Sousa et al, Natural Product Communications, Nov. 2015). We suspect that people vary somewhat in their response, as many readers report benefit but some say soap in bed does not help them.
Another reader experimented with glycerin, a common soap ingredient.
Q. I was troubled with severe leg cramps an hour or two after going to bed on the days when I’d exercised on the rowing machine. Then I read that people get relief by placing a bar of soap under the under the bed sheet near the legs. It worked, but the effectiveness of the soap seemed to diminish over time.
I wondered what might disappear from an ordinary soap bar. The one ingredient I could think of was glycerin. So I bought a bottle of it at the drugstore and tried rubbing some on the skin over my leg muscles, much like applying a moisturizing lotion. I found this eliminated cramping.
I even experimented by leaving one leg untreated; ouch, it cramped! Glycerin has been working for me about a year now. Perhaps others might find it as effective and more convenient than positioning soap bars in bed.
A. We appreciate home experimenters but we doubt glycerin would evaporate from your soap. Fragrance does dissipate and might explain why soap loses its cramp-relieving effects over time.
We have no idea how or why your approach would work, but glycerin is often used in skin care products and should not be harmful. Perhaps other readers will repeat your experiment and let us know how well glycerin works to prevent post-exercise muscle cramps.
Many other readers have described their experience with soap in bed.
“I am an RN who travels from city to city by car. For years I suffered horrible leg and feet cramps after lengthy drives. I heard about the soap regimen and I tried it. To my surprise, it has been over two weeks and I have not had one nocturnal cramp! My cramps were very frequent and it was not uncommon to get 3 or 4 at the same time — feet, toes, and calves — but as mentioned, I have not had one since my first night! And, my cramps were so severe that my toes would actually fan out and would not bend! I don’t know what ingredient is in the soap that causes this success, but personally, I don’t care because it works!”
Brian M. weighed in:
“As a university professor of life science, and a chemist, I have followed this soap discussion for some time with interest. I also suffer from restless legs, and find soap under the bottom sheet helps, but it needs to be a fairly fresh piece.
“A couple of points:
“-Commercial soaps are pretty complex in composition. some of the ingredients are from biological sources, and though purified, still are quite complex and varying from lot to lot. So it is going to hard to point o one ingredient or another and say “that’s it!” Also, it may very well be a combination of ingredients.
“-Possible effects of interest included fragrance (see below), but also perhaps some capacity to reduce static charge on fabrics.
“-If it is a fragrance which works, why wouldn’t soap on the night stand work best? Or does the odor (or other volatile substance) need to be concentrated beneath the sheets? does the “active ingredient” have to be smelled, or come into contact with the skin or the legs? Maybe someone should put a bar of soap in a heavy-duty zip lock bag and try inhaling the fumes given off after a few hours. Or put it in the bedside drawer and open it at bed time?
“-Fragrance can have powerful effects on people (obviously!). I think it was a study at the Monell Institute in PA which showed that prompt exposure to certain smells could abort panic attacks. The most effect substance? Baby powder.
“-Finally, why not dump part of a bar of fragrant soap in the rinse water when washing sheets? Changing to detergents years ago changed clothes washing, because soaps have a natural softening effect on cloth. Maybe wash the sheets (and pajamas) in a soap and see how it works?
“Lots to ponder and experiment with here!”
We haven’t seen any such experiments published, but hope some readers will try one or more.
One reader was quite skeptical until trying soap in bed:
“I don’t believe in hocus pocus but I was desperate. I had horrible leg cramps so I tried a bar of Irish Spring under the covers by my calves. To my disbelief, it works. No more cramps. When cramps start to threaten again, I replace soap with a new bar.”
You can learn more about natural remedies for muscle cramps in our Guide to Leg Pain. Anyone who would like a printed copy, please send $2 in check or money order with a long (no. 10) stamped (71 cents), self-addressed envelope: Graedons’ People’s Pharmacy, No. RLS-5, P. O. Box 52027, Durham, NC 27717-2027.