In trials, the bracelet caught 85 percent of serious epileptic seizures and 96 percent of the most severe cases. That may not sound reliable, but it's far more effective than a conventional bend sensor, which only detected 21 percent of serious attacks. It's also comfortable to wear, helping patients both fall and stay asleep.

The early Nightwatch model sends two separate alerts, one for each symptom. There's work to be done before the two can be combined and increase accuracy. The scientists have already created a company (LivAssured) to sell a finished product, though, and there are plans to coordinate the bracelet with audiovisual systems. Ultimately, the team would like to customize alerts on a patient-by-patient basis, ensuring that even those with unusual symptoms can get timely help.