May 2026, Johns Hopkins School of Medicine, MD, USA neurologists announced in the journal Neurology Open Access that the EpiWatch epilepsy app for the Apple smart watch can reliably detect tonic-clonic seizures as you sleep, with a low false alarm rate.
The brain doctors worked with EpiWatch inc. to test whether their non-EEG based seizure detector could spot the signs of a tonic-clonic seizure and alert a third party consistently. EpiWatch was created by Johns Hopkins scientists, especially for adults and children with epilepsy, and licensed to EpiWatch inc. for product development and distribution. It has already been FDA approved as safe. Now it’s time for the neurologists to show it really works. So how well does this smart watch epilepsy app spot seizures?
What good is a Smart Watch Epilepsy App?
Sleep seizures are very common and can be dangerous, especially for people who sleep alone. Tonic-clonic seizures while you are asleep can increase your risk of sudden unexpected death in epilepsy (SUDEP). People living with epilepsy and epilepsy doctors have found that if a second person is in the room with you while you sleep, and realizes you are having a tonic-clonic seizure in time to help, your chances of SUDEP drop significantly.
The problem is that, for a lot of people, having a nighttime companion is not possible or not something they want. Now epilepsy researchers have developed a smart watch app that monitors your heart rate and movements as you sleep to spot signs that a seizure is brewing. The app, made for Apple Watch, is designed to send an alert to a trusted third party to let them know you need assistance fast. The app also collects data on your seizures so that your doctor can understand the severity and provide better care for you. Importantly, this app has a low false positive rate, meaning you and your family are more likely to get a good night’s sleep and less likely to develop alarm fatigue.
How Did Doctors Test the EpiWatch App?
The trial recruited volunteers with epilepsy to sleep overnight in the epilepsy monitoring unit at one of six hospitals. Each participant would wear an Apple Watch loaded with the EpiWatch app while they slept. Epilepsy doctors would track seizure activity through the night using video-EEG monitoring.
The next morning three independent doctors would use the video-EEG data collected overnight to identify tonic-clonic seizures. Once they knew how many had happened and at what time, they passed the data to the analysis team. They never saw any data from the Apple Watches. Another team of researchers who did not see or know about the results of the video EEG looked at the data recorded by the EpiWatch app and sent them to the study coordinators. Another set of researchers compared the two data sets to see how well the recordings matched the video EEG findings.
Their goal was to figure out how closely the two monitoring methods agreed – the positive percent agreement, and what the false alarm rate was.
Did the Epilepsy Smart Watch App Detect Tonic- Clonic seizures?
The team recruited 242 people to take part; half of the volunteers were aged 18 or younger. Females made up 54% of participants and racial/ethnic backgrounds were representative of the general USA population. Volunteers had different underlying causes of their epilepsy, so the neurologists were able to see whether the device works for epilepsy in general or for subtypes.
The panel of doctors reviewing the video-EEG data spotted seizures in 34% of participants. Overall they found 178 events that they thought might be a seizure. In the end, they decided that 47 of them were tonic-clonic seizures in 37 volunteers. Most of those participants only had one tonic-clonic seizure; 19 of the seizures happened while the participant was asleep.
The EpiWatch app identified 46 out of 47 tonic-clonic seizures. The researchers say the one that was not detected was in a child whose caregiver held their smart watch arm down during the seizure. The team concluded that the Apple Watch app’s success rate was 98% overall, with a 100% positive percent agreement score in children aged 5–12, 95% in 13–21–year–olds and 100% in adults over 22 years.
On average watch detected seizures within 31.5 seconds of the moment when the epileptologists recorded the start of one based on video-EEG data.
EpiWatch for Apple Watch and False Alarms
Next they checked the false alarm rate. Of the participants, 87.2% had no false alarms. The Apple Watch app gave 56 false alarms total in a combined 16,189 hours of study. This translates to a false alarm rate of 0.083 per 24 hours. In other words you would expect to see a false alarm every 12 days. Of the false alarms, 37.5% were caused by motor seizures that did not progress to tonic-clonic seizures. Doctors thought one false alarm was down to a psychogenic seizure. The others corresponded to patients making small, repetitive motions while they played video games and other daily activities.
The EpiWatch app for Apple Watch is available through the Apple App Store for patients with a prescription.
More information
Sleep seizures – Epilepsy Action. July 19, 2023. Accessed June 19, 2026. https://www.epilepsy.org.uk/info/seizures/sleep-seizures
Krauss GL, Elizebath R, Shah S, et al. Phase III Trial of EpiWatch for Tonic-Clonic Seizure Detection in Children and Adults. Neurology Open Access. 2026;2(2):e000111. doi:10.1212/WN9.0000000000000111
