A new skin patch designed to enhance deep sleep by emitting low-intensity sound waves into the brain has shown promise in increasing rapid eye movement (REM) sleep, a stage crucial for mental health and cognitive function. Developed by researchers at the University of Texas at Austin, the device, named NEUSLeeP, is worn on one side of the face during the night and targets the subthalamic nucleus, a brain region involved in regulating REM sleep.

The patch operates by transmitting harmless ultrasound waves through the cheek to stimulate neurons in the subthalamic nucleus, potentially prolonging the duration of REM sleep. Embedded sensors in the device simultaneously record electrical signals associated with sleep, including brain waves, eye movements, and muscle activity, to monitor its effects on REM cycles.

REM sleep, characterized by temporary paralysis of limb muscles and increased autonomic activity, plays a vital role in emotional processing, memory consolidation, and problem-solving. Research indicates that insufficient REM sleep is associated with a heightened risk of depression and dementia. A 2017 study from Boston University School of Medicine involving 351 healthy adults in their 60s found those who developed dementia averaged 17 percent of their total sleep in REM phases, compared to 20 percent or more in those without the condition. Additionally, the onset of REM sleep was delayed in individuals who later developed dementia.

While the causality between disrupted REM sleep and dementia remains uncertain, the overall lack of deep sleep has been recognized as a risk factor for neurodegenerative diseases, which affect nearly one million people in the United Kingdom.

In trials involving 28 healthy volunteers spending several nights in a sleep laboratory, the facial patch increased total REM sleep by nearly five percent and reduced the time taken to enter REM sleep by 24 percent—equivalent to approximately 43 minutes. These findings were recently published in Nature Communications. Researchers plan to conduct larger studies to evaluate whether extending REM sleep through the patch could alleviate symptoms of depression, anxiety, and post-traumatic stress disorder.

Despite the encouraging results, some experts urge caution. Dr. Kirstie Anderson, a consultant neurologist at Newcastle upon Tyne NHS Foundation Trust, noted that the relationship between REM sleep and mental health is complex. She highlighted that certain theories suggest people with depression may enter REM sleep prematurely and that many antidepressants function by delaying or reducing REM sleep. Dr. Anderson also pointed out that, while increased REM is often linked to improved sleep quality, its broader impact on mental health requires further investigation.

Practical considerations may also affect patient acceptance. The patch spans from behind the ear across the cheek, extending toward the forehead and chin, which Dr. Anderson suggested might discourage some users from consistent use. She drew parallels to the high dropout rates—up to 50 percent within a year—seen with continuous positive airway pressure masks used to treat sleep apnea, citing discomfort with facial devices during sleep as a significant challenge.