Next time you have trouble falling asleep, do what mom used to suggest… make yourself all cozy and warm — but perhaps not for the reasons you’d expect. In 1999, Swiss researchers found that temperature in the extremities relative to the core is the most important physiologic predictor of sleep onset — even more so than feeling sleepy. Now researchers at Weill Cornell Medical College in New York City have learned how these warm feelings — especially in your hands and feet — make you sleepy and why it’s not as simple as wearing socks to bed.
In speaking with Matthew Ebben, PhD, sleep expert and psychologist at the Center for Sleep Medicine at New York-Presbyterian/Weill Cornell and a lead researcher in the area of sleep and body temperature, I learned that what’s at work here is not simply the temperature of your hands and feet but rather the physiological process involved in warming extremities. Prior to falling asleep, circulation increases to the periphery, including your hands and feet. Your body cools slightly and sleep ensues.
Dr. Ebben’s recent research focused on the use of biofeedback to teach people how to bring warmth to their limbs. Currently used to treat several medical conditions, biofeedback involves using the mind to influence measurable physiologic aspects — such as lowering blood pressure or raising body temperature. Electrodes were attached to the hands and feet of subjects, all of who suffered from insomnia. Temperature data fed into a computer, displaying the results so subjects could see how well their efforts worked. They were told to use whatever positive imagery they liked to try to increase the temperature of their hands and feet. Specific instructions were avoided, but general guidelines such as “think of the sun” or “imagine a beach” were suggested.
Most subjects quickly learned how to bring heat to their hands and feet. Research currently underway indicates they may fall asleep faster too. There’s no need to wait around for those definitive results, however… this is one technique you can safely try at home. I’d bet you don’t even need a biofeedback device. Just paint a mental picture of the warm sun shining its rays on the paws of those sheep you’ve been counting… and counting… and off to dreamland you’ll go.
