• Posted August 10, 2023

TENS Device Could Ease Sleep Apnea, Freeing Patients From CPAP

A small battery-operated device long used as a treatment for pain may also help patients with sleep apnea, a British study suggests.

Sleep apnea is a condition that impedes breathing during sleep, reduces oxygen intake and undermines sleep itself.

The remedy: zapping sleepers with continuous but controlled electric pulses to open obstructed airways, improve breathing and restore sleep.

“Patients with sleep apnea frequently stop breathing when asleep,” said study author Joerg Steier, a professor of respiratory and sleep medicine at the Lane Fox Unit/Sleep Disorders Center at King's College London.

The condition is often associated with snoring, and often results in fragmented sleep so that patients are excessively tired the next day, Steier said.

To address the problem, patients are usually prescribed a continuous positive airway pressure (CPAP) machine.

During sleep, they wear a mask over the mouth or nose. It's attached to a machine that pumps air in to keep airways open. Though CPAPs help many patients, some struggle to get used to it.

"This treatment only works when people use it," said Dr. Andrew Varga, a neuroscientist and physician with the Mount Sinai Integrative Sleep Center in New York City. “And people can find CPAP machines difficult to tolerate, so they may only use it for some nights, or some portion of the night.”

In fact, researchers pointed out, within three months, 75% of CPAP users stop using it.

For this study, recently published online in eClinical Medicine, Steier's team looked at a low-cost, battery-operated machine available over the counter called TENS. The name is shorthand for transcutaneous electrical neurostimulator.

It stimulates the hypoglossal nerve, which travels from the base of the brain down the neck and ends under the base of the tongue.

At bedtime, users affix electrodes embedded in sticky pads to the base of their neck and upper back. When the machine is flipped on, it delivers continuous light pulses of electricity to nerves and muscles, prompting the airway to stay open.

The technology has already helped patients dealing with the pain of arthritis and childbirth.

Researchers thought it might also work with sleep apnea because of one aspect of the disorder, Steier said. Apnea often involves a loss of tone in neck muscles that normally help keep the airway open during sleep.

The theory, Steier said, was that the electrical stimulation provided by the TENS machine would keep muscles active during sleep. That would increase their tone, keep the airway open and prevent breath-holding, he explained.

Between 2018 and 2023, Steier and his colleagues tried TENS out with 56 sleep apnea patients. On average, the men and women were in their mid- to late 50s.

Roughly half were randomly given portable TENS machines that they could operate themselves at home, fine-tuning the intensity of electrical stimulation that worked best for them. The others continued routine CPAP therapy.

After three months, sleep apnea severity was assessed. Researchers saw an uptick in unobstructed breathing capacity during sleep in the TENS group, and a notable drop in daytime fatigue.

Some had minor side effects. One had mild headaches and a few others had minor skin irritation where the sticky pads were attached to their skin.

Patients who had previously used CPAP tolerated TENS very well, Steier said. But not all patients with sleep apnea stand to benefit.

“We have previously seen that there are responders and non-responders,” he noted. “The larger the neck, the further the patches will be away from the muscles in question. So an elevated body mass index makes it less likely that the treatment is effective.” (Body mass index, or BMI, is an estimate of body fat based on height and weight.)

Such patients can still turn to CPAP therapy, which Steier described as “an excellent treatment" for patients who use it as intended.

He said all patients should first try CPAP, and doctors should seek alternatives only when it fails.

“The use of a simple TENS machine could be a real alternative for those who fail first-line therapy,” Steier said of the study findings. “And we need to consider to develop further methods to control sleep apnea in those who do not continue with CPAP therapy.”

Varga, who reviewed the findings, reacted with cautious encouragement.

“It is not completely clear to me how or why the TENS intervention would work for sleep apnea,” he stressed, adding that in his opinion researchers “do not demonstrate a definitive benefit.”

At the same time, Varga said, the data suggest that TENS intervention may help.

"So yes, I would say it is worth studying further,” he said.

More information

There's more on sleep apnea at the U.S. National Heart, Lung, and Blood Institute.

SOURCES: Joerg Steier, RCP, PhD, professor, respiratory and sleep medicine, Guy's & St Thomas' NHS Foundation Trust, Lane Fox Unit/Sleep Disorders Center, King's College London, U.K.; Andrew Varga, MD, PhD, neuroscientist and physician, Mount Sinai Integrative Sleep Center, and associate professor, Department of Pulmonary, Critical Care and Sleep Medicine, Icahn School of Medicine at Mount Sinai, New York City; eClinical Medicine, Aug. 3, 2023, online