My new favorite Apple Watch and Apple Health metric is one that has been quietly working in the background for years. Specifically, it’s a bit of a hidden Apple Watch feature for tracking a great healthy habit: Time in Daylight. Apple Health automatically tracks Time in Daylight using your Apple Watch Time in Daylight arrived as a metric in the Health app as part of iOS 17 in 2023. Since watchOS 10, Apple Watch has automatically tracked Time in Daylight just by wearing it. The feature works by using the watch’s ambient light sensor to measure your environmental brightness. There’s no app to install or tracking mode to enable (though can you optionally disable it). “Time in Daylight is an estimate of the amount of time spent in sunlight,” Apple explains in the Health app.…