Though I am not a particularly strong supporter of Apple—and you’re welcome to contact me to find out why—I have to admit the Apple Watch could be a useful tool for proactive health monitoring.

The Apple Watch Series 4, released last year, came equipped with an electrocardiogram (ECG) sensor and app to capture the heart’s rhythm. The company did its homework and also obtained clearance from the U.S. Food and Drug Administration (FDA) for the ECG tool around the time of release. Health Canada also issued active licenses for the ECG and irregular heart rhythm notification features on May 16.

Further affirming the feature’s utility, Stanford University School of Medicine shared the early results of a 400,000-participant study during the last week of April to determine if the mobile app could accurately identify atrial fibrillation (AFib). Stanford researchers reported the wearable technology can safely identify heart rate irregularities, which subsequent testing confirmed to be AFib.

This clearance has opened the door for other health-conscious smartwatch applications running on the Apple Watch Platform. They don’t necessarily have to be directly cardiac related, either. For example, on May 21, NightWare Inc., a Minneapolis-based startup that develops digital therapeutics for mental health, received FDA Breakthrough Status for its NightWare product, which measures and treats nightmares for sufferers of post-traumatic stress disorder (PTSD).

Among the many other disconcerting symptoms of PTSD, it is estimated that almost 5 million Americans suffer from Nightmare Disorder related to PTSD. Nightmares and Nightmare Disorder have long been associated with a slew of worrisome effects—increased suicidality, heightened heart disease risk and diabetes, and cognitive difficulties like memory loss, anxiety, and depression. A single nightmare event is enough to make anyone anxious or upset, but repeated nightmares and interrupted sleep can bring PTSD sufferers’ trauma to the forefront nearly every night.

For those unfamiliar with what a Breakthrough Designation means, it occurs when the FDA recognizes a therapeutic solution for a life-threatening condition for which no currently approved treatment is able to offer similar benefits to the proposed therapy. This designation allows the FDA to grant priority review when preliminary clinical trials indicate a given therapy might offer substantial advantages over existing options for patients with serious or life-threatening diseases. A breakthrough therapy designation is requested by the company providing the solution. In some cases, the FDA may suggest the sponsor consider submitting a breakthrough request if, after reviewing the submitted data, the agency thinks the program might meet breakthrough criteria and the development program will benefit from the designation.

“This is truly a watershed moment for our company,” NightWare CEO and founder Grady Hannah told the press. “In our initial studies, NightWare has demonstrated substantial and significant efficacy. The FDA’s Breakthrough Status designation will enable us to complete our Randomized Clinical Trials ahead of schedule and give us the opportunity to help improve the lives of veterans and others suffering from PTSD sooner than we anticipated. Our team is humbled and excited by this FDA designation.”

The NightWare application operates by tracking, intervening, and processing nightmare events. As the wearer slumbers, the app continuously analyzes heart rate, accelerometer, and gyroscope data collected from the Apple Watch’s integrated sensors to learn sleep patterns in the first few days of wearing the watch each night. The “learning period” usually takes less than 10 days to apply machine learning algorithms for a profile of the individual’s sleep patterns. A “stress threshold” is computed during this time based on spikes in heart rate and movement, indicating a nightmare event has begun.

Once the learning period is over, whenever the application detects a potential nightmare it intervenes by vibrating (also called vibrotactile feedback). The watch will vibrate enough to arouse the sleeper out of sleep without waking them. The intended result is the nightmare is interrupted by the sudden arousal without interrupting the sleeper’s circadian sleep pattern, allowing for high quality, more restful sleep.

The app begins with low-intensity vibration. But if it detects the nightmare event has not been halted, the app increases the intervention intensity. The watch app also sends the collected data to a secure cloud service to facilitate review by a healthcare professional. NightWare also comes equipped with a desktop app to display stress, intervention, and other collected data. Tech-savvy individuals can use the desktop app to review their data, or a healthcare professional could use it to review data for multiple users.

“We’ve seen a markedly large effect size for improved sleep quality in NightWare open label trials,” NightWare Chief Medical Officer Daniel Karlin, M.D. commented to the press. “We are excited to get folks enrolled in these randomized trials to further verify the observed efficacy.”

NightWare is early in development and currently not available for sale. The company is currently enrolling patients in two randomized clinical trials (RCT), one of which is being conducted at VA hospitals in Minneapolis and St. Cloud, Minn. The company is also enrolling in a virtual RCT trial broader in geographic scope. If interested, prospective participants can get more information about enrollment at http://bit.ly/2W1it51.