The Sleep app not only tracks your Sleep, it helps you create a bedtime routine and schedule. See The time you spent in REM, Core and Deep Sleep, as well as when you might have woken up. Unusually high or low heart rates and irregular heart rhythms (known as arrhythmias) could be signs of a serious condition. But many people don’t recognize The symptoms, so the underlying causes often go undiagnosed Notifications in the heart rate app will alert you to these irregularities so you can take action and consult your doctor. With The ECG app, Apple watch is capable of generating an ECG similar to a single-lead electrocardiogram. It’s a momentous achievement for a wearable device that can provide critical data for doctors and peace of mind for you. Apple watch has an innovative sensor that tracks your temperature while you sleep. Cycle Tracking uses this data to provide a retrospective estimate of when you have likely ovulated, which can be helpful for family planning. As always, your data is private and secure.