How To Decode Your Wearable Data, According To A Performance Medicine Doctor

It seems that everyone has at least one device they wear regularly that tracks some aspect of health-related behavior. It could be an Apple Watch tracking how often they take deep breaths and move, an Oura ring tracking sleep, a Whoop band assessing exercise intensity and "strain," or a Fitbit tracking steps. We have become quite the human data repositories. But other than providing the companies collecting this data with valuable insights into our habits, what else can be gained from all of this? 

Some don't glean much from their wearables other than the occasional glance to check step count. Others try to understand what it says about their sleep routine, dietary habits, or fitness regimen—then, after a couple of weeks, they stop checking, unsure what to do with that information.

As a physician specializing in personalized performance medicine, I love data. Peter Drucker, an expert in business process optimization, supposedly said something akin to "you manage what you measure," and while this may not be true in all cases, it does apply to your health when you are trying to improve it.

For example, we know that maintaining healthy blood pressure levels can affect cardiovascular health outcomes1. That is why we have blood pressure checks as a routine part of a physical exam. Similarly, waist circumferences, blood sugar levels, and more can be markers of metabolic health.

Even beyond improving health, measuring particular metrics and managing your lifestyle habits based, in part, on them can help you achieve your broader performance goals (such as wanting to be more focused or energetic, win a race, or perhaps perform better at work). Some of these wearables can give you insights into how your behaviors—around sleep, stress management, or physical activity, for example—may affect how successful you are at achieving those goals.

While we can manually keep track of what time we go to bed and when we wake up, what matters is the amount of time we are actually sleeping between those two events. It is also important to have sufficient time in the most restful states of sleep: deep sleep and REM sleep. That is what determines sleep quality. Deep sleep is important for physical rest, and REM sleep is especially important for creativity and mental rest (such as cementing memories).

The insight into your sleep quality obtained from some wearable devices can be very helpful if you use them to assess what behaviors affect your ability to get the quality and quantity of sleep you need to perform at your best.

How to best use a tracker for sleep? Don't just measure your slumber time—also keep track of behaviors that may be affecting your sleep quality or quantity. For example, we know that the timing of meals, pre-bed screen time, drinking alcohol or caffeine, and working from bed can all affect sleep.

In order to get the most from your sleep data, compare it to these other behaviors, which you may have to track manually. Looking at this data side by side may enable you to see what has the most impact on your sleep, which will be different from someone else. 

Does the number of steps you take really affect your health or your performance goals? In a word: yes.

We know that physical activity is extremely important in staying healthy, yet only 20% of Americans get the recommended 150 minutes a week. Many of us overestimate the amount we actually do get, so the tracker can keep you honest with yourself.

Heart rate variability (HRV) is a metric proven to reflect your stress level4. This is because when you are stressed, your sympathetic nervous system is in high gear. Normally we have a nice high level of variability in our heart rate, but when our nervous system is in stress mode, that variability goes down as our heart rate stays higher, anticipating that need to fight or flee. Being in this state for long periods of time means the body is focused on survival rather than taking care of maintenance functions, including immunity and digestion. Thus, low HRV means those systems aren't working optimally. Not to mention, stress affects aging for the body and brain.

The way to best use this metric is not to compare yourself to others but rather to compare yourself to, well, yourself. Try different strategies to get that HRV higher–meditation, breathwork, exercise, or journaling, for example.