Nightmare disorder is exactly what it sounds like: a condition in which people regularly experience nightmares when they sleep, which affects both their sleep and their ability to wake up. People who experience nightmare disorder may be afraid to go to sleep at all.

In order to help people with this terrible condition, a new prescription-only app has been developed that works with the Apple Watch to help patients get through the night. If granted a prescription to the app, NightWare, the patient downloads the app to an Apple Watch and starts wearing it while they sleep.

Before the app can treat the patient, its built-in AI software first needs to learn the wearer’s sleep patterns, which can take three to 10 days. After the learning the period, NightWare can sense when a nightmare may be about to start based on the wearer’s heart rate and movement. The Apple Watch will then intervene just prior to the nightmare with a vibration that is just strong enough to prevent it from happening but not enough to wake up the wearer. Should the vibration awaken the wearer, the app will adjust and vibrate less the next time a nightmare is on the horizon.

So, how effective is the NightWare app? In a 30-day trial involving 70 patients with PTSD-related nightmare disorder, patients who used the NightWare app experienced significantly better sleep quality than those who wore the Apple Watch but didn’t receive any vibrations.

Digital therapeutics like NightWare have enormous potential for the medical industry. For one, they are low-risk and are unlikely to produce unwanted side effects. Secondly, they will allow doctors to collect real-world data from patients, which will help them develop better treatments for a range of conditions.

As for the NightWare app, a larger trial involving 240 patients from several Department of Veterans Affairs hospitals is currently underway. If the results are successful, the app could start helping people with Nightmare disorder get a good night’s sleep in the near future.