I have not come across this app before, but it was really neat to read about it on Apple Newsroom this morning:
NightWare is a digital therapeutic system that works in conjunction with Apple Watch and iPhone to disrupt nightmares related to post-traumatic stress disorder. Available by prescription only, it’s also the first and only digital therapeutic developed specifically to treat nightmares that is cleared by the FDA. NightWare uses information from the Apple Watch heart rate sensor, accelerometer, and gyroscope to detect a nightmare and then disrupt it through haptic feedback, generating gentle pulses on the wrist that gradually increase until the user is roused from the nightmare, but not from sleep.
This sort of thing is consumer technology at its best.