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Smartwatches, rings, patches, you name it — wearable devices have exploded in use in the last decade, and so have the health metrics they measure. Sure, you can still count your steps, but now you can also track the number of hours of REM sleep you got last night, and don’t forget to check your heart rate variability before working out today.
But here’s the thing — more data is not always better. Is this flood of information about your health actually making you, well, healthier, or is it just overwhelming?
Are wearables accurate?
Wearables are devices equipped with sensors that measure your activity and physiological data —things like heart rate, blood sugar and blood oxygen levels. But let’s get one thing straight: Your smartwatch or ring is not a medical device. The sleep score you get every morning from your ring, or the electrocardiogram (EKG) on your watch, is not the same as measuring your sleep or heart activity in a medical setting.
Take the EKG, for example. If you get an EKG at the doctor’s office, 12 different leads will be placed on your body to analyze your heartbeat. The EKG on your smartwatch is roughly equivalent to just one of those 12 electrodes. It gives you some of the data, but not the full picture.
Some wearable devices are more sensitive and reliable than others, and for basic measurements, like step count and heart rate, they’re generally accurate. But for more complex and combined metrics, you should take the number your device gives you with a grain of salt.
“Generally, the fancier the number, the more skeptical you should be of its reliability alone,” says Cindy Lin, MD, clinical professor of sports and spine medicine and director of The Sports Institute at UW Medicine.
That said, there are ways that wearable devices can help your health.
How can wearable devices improve your health?
While wearable devices aren’t as precise or reliable as medical tests, that doesn’t mean you can’t learn about your health from the data they produce.
Tracking trends
Many wearable devices now give you a daily score for things like your activity, sleep and recovery, but it turns out those aren’t the best numbers to pay attention to.
“A lot of these scores are just algorithms made up by the companies, and they don’t have a lot of data behind them,” says Jordan Prutkin, MD, MHA, MHS, the medical director of the UW Heart Institute, and associate director of the UW Center for Sports Cardiology.
On the other hand, paying attention to trends in your data over time can reveal insights into your health.
“If that data is consistent and it’s deviating from the baseline, it can provide us some insight into how people are feeling,” says Natalia Usoltseva, MD, clinic medical director at UW Medicine Primary & Urgent Care at Ballard.
So, for example, a single pulse oximetry reading from a wearable is probably not worth paying attention to, but a consistent trend could be telling you something.
“If someone is getting notifications night after night that their oxygen is low, they probably should be checked by their physician for obstructive sleep apnea,” says Usoltseva. “Again, it’s not a diagnostic tool, and it can be wrong, but it can help us to get the proper testing done.”
Screening for underlying health problems
One area where watches do a pretty good job is screening for heart conditions like atrial fibrillation.
“I have several patients who felt something was wrong with their heart, but only got the diagnosis of AFib because their watch alerted them for it,” says Prutkin.
Usoltseva also has had patients who didn’t have symptoms but were diagnosed with AFib after coming to the doctor because of warnings from their wearables.
Even the EKGs on these devices, while imperfect, can give doctors valuable information.
“It can’t tell you if you’re having a heart attack, but it’s pretty good for people who say that their heart rate is going too fast, too slow or irregular, and trying to help figure out what the cause might be,” Prutkin says.
Motivation to make healthier decisions
Exercising, getting enough sleep and managing stress are all extremely important for your health. But tracking metrics like sleep stages, heart rate variability, and VO2 max are really only helpful if they motivate you to make healthy choices.
“There’s a sense of empowerment when you know more about your body,” says Prutkin. “The question is how we use that data to actually make changes that are beneficial for improving health.”
Say you start tracking your sleep on a wearable and realize you’re not getting very good shut-eye.
“Maybe you say, ‘I want to ensure that I’m getting better sleep, so I’m going to look at everything I do during a day, including my alcohol intake, my caffeine intake and all these other factors that may influence sleep,’” says Prutkin. “That may be a good use of your data and your wearables, if that’s a road that you want to go down.”
On the other hand, if you continue drinking 5 p.m. espressos and scrolling on your phone late into the night, there’s not much point to your watch telling you you’re sleeping badly. After all, if you didn’t sleep well, you probably don’t need a sleep score to tell you so. If anything, it could make you more anxious to see your poor sleep scores day after day and potentially even contribute to insomnia.
Similarly, if your smartwatch is motivating you to move more throughout the day, which is helping you manage stress and be less sedentary, those are real benefits. But if your watch’s unmet goals are just making you feel bad for not getting to the gym more during a busy time in your life, that’s defeating the purpose.
5 tips for how to use wearable devices effectively
So how can you use wearable devices to improve your health and avoid just getting more anxious about it? Here are some tips.
Figure out your why
We’re in an age of data, but more data is not always better.
“The goal of exercise is not to try to get your resting heart rate down. The goal of exercise is to make you feel better and help you live longer,” says Prutkin. “With all of the data from the wearables, the question is really, ‘How is it going to change how you live your life? How is it going to change your actions?”
So, before you start using a wearable device, take some time to think about what your goal is.
“Wearables often work best when layered onto a more lasting goal — like training for a race, improving mental health or building a routine,” says Lin.
Choose relevant and reliable numbers
Once you know why you’re using your smartwatch or ring, then you can choose which metrics are actually going to be helpful to pay attention to.
If your goal is just to move more throughout the day for your physical and mental health, your weekly step count or resting heart rate trend can tell you most of what you need to know and are more reliable than advanced metrics.
On the other hand, if you’re training for a half-marathon, looking at your VO2 max increasing over time might build positive reinforcement and help motivate you to keep up with your training runs.
Don’t compare your metrics to others
Your body is unique, and so are your health metrics, whether it’s your resting heart rate or the amount of sleep your body needs.
“I do think it’s really important to recognize that you shouldn’t be comparing yourself to other people — my numbers aren’t relevant to you,” says Prutkin.
So if your wearable says your VO2 max is “below average” for someone your age, or if a sleepmaxxer on social media says you need to be getting 10 hours of sleep every night, don’t pay attention to that. Trust your own body and what it needs, and base your conclusions on your own baseline and trends.
If you’re getting obsessed, trust your body and take a break
If you feel like you’re constantly checking your health data on your device, it could be time for a break.
“The irony is that obsessing over health metrics can create the very problems you are trying to prevent. When you stress about a sleep score, your body activates its stress response, which makes sleep worse,” says Lin. “If you feel relieved when your wearable numbers are good and crushed when they are not, then the wearable might not be helping you to better health.”
Take your watch off for a few days and see how you feel. Ask yourself why you need the data from your wearable — is it changing your behavior for the better or just making you more anxious?
Trust your body
Prutkin himself uses his smartwatch to log miles on runs, but he decided to stop tracking all of his other health metrics.
“In the end, I decided personally that it didn’t affect me and my health, and it wasn’t making me live a healthier lifestyle to have this information,” he says.
Putting on a smartwatch or ring does not automatically make you healthier. First, you need to understand why you’re using it and which trends — not individual data points — will be helpful to pay attention to. After all, your body is much more intelligent than any device.
“If you don’t feel well, you don’t feel well, you don’t need a number,” says Usoltseva. “Listening to your body, feeling what is normal for you — that is more important than the number on a watch.”
