I was recently reminded of an "old wive's tale" that a bar of soap under the bed sheet can reduce everything from muscle cramps and restless leg syndrome to arthritis. As ridiculous as it sounded to me, I scoured the internet, and was astonished at how many people were claiming this trick works.
What Do People Claim?
Some say they use a small bar of soap, while others chose a large bar. Some put the soap under the sheet, others put it in a sock between their knees. Some even claim the shavings of soap under the sheet worked just as well as a full bar of soap.
Some soap was scented and others were unscented, but worked just the same. Some were are adamant that only a particular brand of soap worked for them (e.g. Ivory vs. Irish Spring). Of course, several people did challenge the "old wive's tale" entirely, and say it did not work for them at all.
Our famous doctors have chimed in on the matter. Over a decade ago, Dr. Peter Gott recommended putting a bar of soap under the sheet for restless leg patients. Dr. Oz emphasized the benefit of a bar of soap, specifically lavender, for restless leg syndrome due to the relaxing lavender scent.
What Does the Science Say?
Several studies have found a mild, calming effect of lavender and other scents.6,8,9,11 One study even jacked mice up on caffeine, and then watched the scent of lavender sedate them back to a normal state.1 Maybe Starbucks can create a lavender scented coffee.
Also, there has been suggestion, albeit inconclusive, that lavender can calm muscles, even those that contribute to flatulence.2 Good to know.
A recent study showed a lavender oil massage reduced self-reported restless leg symptoms compared to a no massage group of hemodialysis patients.8 However, it is not clear if this improvement was actually due to the oil, or the massage – since a warm massage, alone, has been shown to improve restless leg symptoms in diabetic patients.3
Beyond one anectdotal study,4 found no research studies that directly tested the potential myth of putting a bar of soap in the bed.
Two studies have shown the benefit of soap scented patches (from soap fragrances, but not actual soap) on both menstrual cramps and fibromyalgia.12,13 However, the research hypothesizes that the active ingredients in the skin patch is the scent itself.”13 In other words, the researcher concludes that the scent is not working through actually smelling it, but by being absorbed through the skin.
This would be a quite unique method of medicinal delivery – if it is actually confirmed. A lab study found that lavender essential oil could reduce a muscle twitch, when applied directly to animal muscles, in vitro,10 so maybe it is possible. Time will tell.
I have read that some consider magnesium in soap as the reason it works, but even if magnesium from a bar of soap that is under a bed sheet could somehow get inside the person sleeping in the bed, the research on magnesium does not support that it helps with muscle cramps, anyway.5
Besides, much more magnesium could come from a healthy diet of sensible combinations: almonds, artichokes, avocado, cashews, pumpkin seeds, spinach, sunflower seeds, or Swiss chard (for example).
What Does Common Sense Say?
At this point, I think we have two conclusions we can draw:
- Certain scents, such as lavender, can have a MILD calming effect in SOME people, which could reasonably and subsequently lessen perceptions of restless legs, cramps, or possibly arthritis. However, many people have claimed benefits from unscented soap, which would rule out any effects of the scent.
- In this case, the more reasonable explantation is that the bar of soap in the bed plausibly works, because we believe it is going to work - aka. “The Placebo Effect”.
As we learned with Ionic Energy Bracelets, if the soap in the bed gives someone relief and hope, despite most likely due to a placebo effect, then why not let them enjoy it?
- Buchbauer, G., Jirovetz, L., & Jäger, W. (1991). Aromatherapy: evidence for sedative effects of the essential oil of lavender after inhalation. Zeitschrift für Naturforschung C, 46(11-12), 1067-1072.
- Cavanagh, H. M. A., & Wilkinson, J. M. (2002). Biological activities of lavender essential oil. Phytotherapy Research, 16(4), 301-308.
- Charlet Asenth, M., & Thenmozhi, P. Effectiveness of warm massage on restless leg syndrome among patients with diabetes mellitus. International Journal of Multidisciplinary Research and Development, 3(8), 142-144.
- Clarke, E. A., & Bawa, S. (2015). Safer Sleeping with Soap? Quinine, Cramps and Weighing Up Anecdotal Evidence. Annals of the Rheumatic Diseases, 74(Suppl 2), 625-625.
- Garrison, S. R., Allan, G. M., Sekhon, R. K., Musini, V. M., & Khan, K. M. (2012). Magnesium for skeletal muscle cramps. The Cochrane Library.
- Goel, N., Kim, H., & Lao, R. P. (2005). An olfactory stimulus modifies nighttime sleep in young men and women. Chronobiology International, 22(5), 889-904.
- Hashemi, S. H., Hajbagheri, A., & Aghajani, M. (2015). The Effect of Massage With Lavender Oil on Restless Leg Syndrome in Hemodialysis Patients: A Randomized Controlled Trial. Nursing and Midwifery Studies, 4(4), e29617.
- Herz, R. S. (2009). Aromatherapy facts and fictions: a scientific analysis of olfactory effects on mood, physiology and behavior. International Journal of Neuroscience, 119(2), 263-290.
- Lehrner, J., Marwinski, G., Lehr, S., Johren, P., & Deecke, L. (2005). Ambient odors of orange and lavender reduce anxiety and improve mood in a dental office. Physiology & Behavior, 86(1), 92-95.
- Lis‐Balchin, M., & Hart, S. (1999). Studies on the mode of action of the essential oil of LavenderLavandula angustifolia P. Miller. Phytotherapy Research, 13(6), 540-542.
- Moss, M., Cook, J., Wesnes, K., & Duckett, P. (2003). Aromas of rosemary and lavender essential oils differentially affect cognition and mood in healthy adults. International Journal of Neuroscience, 113(1), 15-38.
- Ough, Y. D., Albert, R., Bhaskar, D. D., Jones, G. T., & Loftus, K. (2008). Soap-scented skin patch for menstrual cramps: A case series. The Journal of Alternative and Complementary Medicine, 14(6), 618-618.
- Ough, Y. D. (2008). Soap-scented oil skin patch in the treatment of fibromyalgia: A case series. Journal of Multidisciplinary Healthcare, 1, 59.