The Apple Watch Health Data You Should Share With Your Doctor

A week after dislocating my ankle, I found myself back at the hospital with pain in my calf. Noticing my Apple Watch, the emergency physician asked if I had received any high heart rate notifications, one of the heart monitoring features offered by the Watch and a symptom of a possible blood clot. I’ve been wearing an Apple Watch for years, revelling in the sheer volume of stats it provides during and after my workouts. But this was the first time a doctor had shown interest in the data it was collecting.

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While Apple Watch data isn’t intended to diagnose health conditions, it can provide an early warning when a change in health has occurred, and help track symptoms, sleep patterns and more. A data set of that nature makes it easier for physicians to evaluate health risks, says Dr. Steven Grover, professor in the Department of Medicine at McGill University in Montreal.

Here are three data points worth sharing with your doctor.

Any irregular heart rhythm warnings

One of the most important health functions of the Apple Watch is its ability to detect potential atrial fibrillation, a.k.a. AFib, a type of irregular heartbeat that affects about 200,000 Canadians, says Dr. Paul Piechota, a family physician and medical director at Access Med in Kirkland, Que.

“The biggest concern [with] is that there is an increased risk of stroke due to blood clot formation in the heart,” he says. “Many patients with atrial fibrillation don’t have symptoms so detecting it through methods such as the Apple Watch can identify the condition early.”

Once the option to monitor heart activity has been enabled, heart rate sensors and electrodes embedded in the back of the Watch check your heart rate at regular intervals. If an irregular rhythm or unusually high or low heart rate are detected, the watch sends a notification, which is useful information to discuss with your doctor.

Piechota notes that AFib is episodic—meaning it might not be picked up by a routine electrocardiogram (EKG)—which is why the Apple Watch’s constant monitoring can be helpful. However, bear in mind that not all irregular rhythms picked up by the Watch indicate a serious problem.

Abnormalities in your menstrual cycle

With your input—plus heart rate data collected by the Watch—Apple’s Cycle Tracking app can help predict both the arrival of your period and your fertile window. (You’ll also never be at a loss again when your doctor asks you for the date of your last period.)

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Apple Watch 8 and Apple Watch Ultra can also capture wrist temperature data, and use it to provide a retrospective ovulation estimate, which can be used to see if, in previous menstrual cycles, your fertility window and sexual activity have overlapped. This can be helpful for family planning (and family planning-related convos with your doctor).

The Cycle Tracking app can also pinpoint any potential deviations in your cycle, which might indicate an underlying condition such as PCOS, fibroids or a thyroid problem. After reviewing your cycle history to confirm whether a deviation has occurred, you can export the last 12 months of your cycle history to share with your healthcare practitioner.

Your sleep data

In conjunction with the Sleep app on your phone, your Watch tracks your respiratory rate during sleep, which can help detect disruptions in breathing, a potential indicator of sleep apnea. Sharing this information with your doctor could help them determine whether you need sleep apnea testing.

Related: Why You're Not Sleeping—And How To Fix It

Dr. Marc Baltzan, a sleep medicine expert and associate professor at St Mary's Hospital, part of the McGill University network in Montreal, says that alongside the Watch’s data on oxygen levels during sleep, he also studies a patient’s symptoms and validates these results with a sleep study when diagnosing sleep apnea.

“Apple Watch [data] the only way to establish a certain diagnosis” he says. “But it's a pretty good clue that something's wrong.”