Scientists have developed a soft patch that may offer a new way to improve an important stage of sleep without using drugs or surgery.
In an early human study, people using the device entered rapid eye movement, or REM, sleep sooner and spent more time in it.
The technology, called NEUSLeeP, was developed by researchers led by the University of Texas at Austin. The study involved 28 adults, and the findings were published in the journal Nature Communications.
Sleep is not a single, uniform state. During the night, the brain moves through several stages that repeat in cycles, including lighter sleep, deeper non-REM sleep and REM sleep.
REM is the stage most closely associated with vivid dreaming. During REM, brain activity becomes relatively active, while most of the body’s large muscles are temporarily relaxed.
Scientists believe REM sleep contributes to learning, memory and emotional processing. Problems with REM sleep have also been observed in people with conditions such as depression, anxiety and post-traumatic stress disorder, although sleep changes can differ greatly from one person to another.
The new device is designed to do two things at once. It records electrical activity from the brain and delivers gentle ultrasound stimulation through the skin.
Ultrasound uses sound waves at frequencies above the range people can hear. Medical ultrasound is already widely used for imaging, but carefully controlled ultrasound can also be studied as a way to influence activity in the nervous system.
One attraction of this approach is that ultrasound may reach deeper brain areas than some other noninvasive stimulation methods. The researchers say NEUSLeeP was designed to influence brain regions involved in REM sleep while monitoring the brain’s response in real time.
The patch is soft and attaches to the skin, making it very different from large laboratory machines normally used in sleep research. The long-term goal is to create technology that could potentially be used in more natural settings, including the home.
In the study, researchers tested the patch in 28 people. The group included healthy sleepers as well as people reporting some sleep difficulties.
On average, stimulation was associated with participants entering REM sleep 43 minutes earlier. They also spent about 16 minutes longer in REM sleep.
Those differences are notable because sleep stages are normally influenced by many factors, including age, stress, medications, alcohol, illness and a person’s normal sleep schedule. A device capable of changing REM sleep without medication could therefore be useful both for research and, eventually, treatment.
The researchers reported minimal adverse effects, and participants generally found the patch comfortable. Safety is especially important for any technology designed to be used while a person is asleep and potentially outside a medical center.
The team also observed changes beyond sleep timing. Among healthy participants, stimulation was associated with increased heart rate variability.
Heart rate variability measures small differences in the time between heartbeats. It is influenced by the nervous system and is often studied as one sign of how the body adjusts to stress and changing demands.
Brain imaging also showed changes in networks associated with emotional processing. These findings led the researchers to suggest that improving REM sleep might eventually have effects on stress regulation and emotional health.
However, those possibilities remain preliminary. The study was not designed to prove that the patch treats depression, anxiety, PTSD or other mental health conditions.
Gregory Fonzo of Dell Medical School, one of the project’s co-principal investigators, noted that REM sleep may be involved in emotional recovery and adaptation to stress. The researchers now want to test whether changing REM sleep can produce meaningful improvements in people with specific disorders.
The team plans larger studies involving chronic insomnia, depression and PTSD. These trials will be important because a result in 28 participants is encouraging but too small to establish how well the technology works across different populations.
Researchers will also need to understand whether the effect continues with repeated use. It is possible that the brain could respond differently after days or weeks of stimulation than it does during a short research study.
Another important question is whether increasing REM sleep is beneficial for everyone. Healthy sleep depends on a balanced pattern of sleep stages, and simply maximizing one stage may not necessarily produce better health.
The study’s main strength is that it combines stimulation and monitoring in one wearable system. Rather than delivering stimulation without knowing what the brain is doing, the technology offers the possibility of adjusting treatment according to a person’s changing brain activity.
This could eventually support more personalized sleep treatments. For example, future systems might identify when a person is approaching a particular sleep stage and deliver stimulation only when needed.
Still, NEUSLeeP is an experimental device, not an established treatment that people can currently use to manage sleep disorders at home. Larger controlled trials, longer safety monitoring and regulatory review would be required before routine medical use.
The University of Texas team is already considering how the technology could move beyond the laboratory. The researchers are working with Discovery to Impact, UT Austin’s commercialization group, and a patent application has been filed.
Overall, the Nature Communications study provides an intriguing proof of concept. A soft wearable device appeared able to change REM sleep in people without medication or surgery, but the clinical meaning of those changes remains to be established.
If larger trials confirm the findings, the technology could become useful for sleep research, home monitoring or treatment of selected sleep and mental health problems.
For now, its biggest contribution is showing that deep brain activity linked with sleep may be influenced and measured using a relatively compact wearable system.
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