On Monday while at its Worldwide Developer Conference, Apple debuted WatchOS 9, a major update coming to the Apple Watch.

Every summer in June, Apple holds a WWDC keynote to unveil the latest operating system updates to all its platforms - including WatchOS. This year, Apple took the wraps off WatchOS 9 and led its presentation by announcing it improved the Apple Watch’s ability to detect arterial fibrillation (AFib), an irregular heartbeat disorder that causes heart-related complications. With WatchOS 9, supported Apple Watch models can now offer an AFib History feature - to show you how often you experience AFib over time.

Apple said it was granted 501(k) approval from the FDA. It's not a full approval, so Apple wasn't required to provide effectiveness data from clinical trials.

Other new health features for Apple Watch include the ability to show heart zones to better understand your intensity level, features to set up distance and time intervals, and haptic and voice feedback so you can better tell when modes have switched during an exercise. Some Apple Watches are also getting new complications and watch faces (including astronomy faces), form metrics for runners, and a new workout type for triathletes that can automatically switch between cycling, swimming, and running.

Apple has also included new sleep tracking features. With Sleep Stage, WatchOS 9 can detect REM, core, and deep sleep stages. Apple said you will see sleep stage data on Apple Watch in the Sleep app and can view more information - such as time asleep and additional metrics like heart rate and respiratory rate - in sleep comparison charts in the Health app on iPhone.

WatchOS can also track medications and notify you when you need to take them in the Apple Health app. "The new Medications experience on Apple Watch and iPhone helps users manage and track their medications, vitamins, and supplements, allowing them to create a medications list, set up schedules and reminders, and view information on their medications in the Health app', Apple said. "The Medications app on Apple Watch makes it easy for users to conveniently and discreetly track medications anytime".

Finally, if you own a Meta Quest VR headset, Apple said the Apple Watch Watch can now show stats from Move, Meta’s fitness tracker for the Quest, on the Fitness mobile and Watch app.

Oh, and apps in WatchOS 9 can be pinned for quick access.

Apple hasn't revealed yet which Apple Watch models can run WatchOS 9. But WatchOS 8 supported the Apple Watch Series 3 and up. The developer beta of watchOS 9 is available to paid Apple Developer Program members at developer.apple.com starting 6 June 2022. A public beta will be available for free to watchOS users in July at beta.apple.com.