Could tracking your resting heart rate before bed predict how well you’ll sleep that night? Longevity influencer Bryan Johnson thinks so.

“I’ll look at my heart rate and see how many times it’s beating per minute,” Johnson told Chris Cuomo during a televised town hall last week. “It is the best indicator of how I’m going to sleep and of my overall health.”

It’s a tempting theory, especially because most people have that information readily available on their wrists with Apple Watches and other health trackers—but how much weight does it hold?

What Your Resting Heart Rate Actually Tells You

Your resting heart rate is a great general indicator of basic heart health and fitness—it’s the number of times your heart beats per minute when you’re relaxed and not moving. Most healthy adults have a normal resting heart rate between 60 and 100 beats per minute (bpm), while highly conditioned athletes can have a resting heart rate as low as 40 bpm.1

Your heart rate changes throughout the day and from day to day based on a variety of factors. “Heart rate is closely tied to other things that are going on,” Luis F. Buenaver, PhD, director of the Behavioral Sleep Medicine Program at Johns Hopkins, told HEALTH. Stress, caffeine, medications, alcohol, and illness can all increase your heart rate, while relaxation techniques can lower it.

Before bed, a lower heart rate generally reflects that your body is shifting into a more relaxed state that’s more conducive to sleep—but being relaxed isn’t necessarily the same thing as sleeping well.

Resting Heart Rate and Sleep Quality

Noting your resting heart rate before bed may be a helpful piece of data, but it’s not necessarily the best or only indicator of how well you’ll sleep. While an elevated heart rate shows that your nervous system is aroused—which can make it harder to sleep—a high heart rate doesn’t always mean you should expect to sleep badly.

Your resting heart rate “is better viewed as a physiologic readiness for bed,” Henry Yaggi, MD, MPH, director of the Sleep Medicine Program at Yale, told HEALTH.

Many of the same things that interfere with sleep—like stress, drinking alcohol, or eating too close to bedtime—can also raise your heart rate. That means an elevated heart rate isn’t necessarily causing poor sleep; instead, it may simply reflect other factors that are affecting both. As Buenaver put it, “If your heart rate is elevated, the question is, why?”

While other helpful pre-bed metrics include heart rate variability (the tiny differences between each individual heartbeat) and blood pressure, experts say the best predictors of sleep may not be measurable by a health tracker. Instead, more subjective factors—like how much exercise you got during the day, how stressed you are, or how relaxed you feel before bed—can be just as strong in predicting sleep quality, said Buenaver.

How rested you feel in the morning is also a good sign of how well you slept, regardless of what your heart rate predicted before bed. “As long as you feel refreshed and are functioning, that’s good quality sleep,” said Yaggi.

Should You Check Your Heart Rate Before Bed?

Measuring heart rate before bed can offer insight into how relaxed you are, but relying on it to predict sleep quality could backfire. If you see that your heart rate is elevated before bed—and you begin to worry that you may not get a good night’s sleep because of it—you may inadvertently prevent yourself from sleeping well.

Experts say sleep anxiety and an outsized focus on controlling and optimizing sleep are becoming more common. Some sleep experts refer to this as orthosomnia, an unhealthy fixation on achieving “perfect” sleep that’s fueled by data from wearable devices. “With the ramping up of wearable technology, we’re seeing patients come into the clinic really anxious and unable to fall asleep because their sleep tracker says that they won’t,” said Yaggi.

Instead of relying on metrics to optimize your sleep, experts recommend prioritizing good sleep hygiene, like staying off screens before bed, keeping a consistent sleep schedule, exercising frequently, and limiting food and alcohol close to bedtime.

If you must try looking at your heart rate before bed, “look at it more as an indicator of ‘are you relaxed enough to go to bed?’” said Buenaver—and if it’s high, use it as a signal to do some relaxation exercises before going to sleep.