You likely pay attention to at least a few of your Fitbit’s health metrics every day, but there’s one little gem of data called heart rate variability or HRV that too often gets overlooked.
Knowing your heart rate variability (HRV) and how it changes over time provides key insight into how your heart functions and how your body responds to physical or mental stress, illness, exercise, and activities of daily living. HRV is also a key metric in how your body recovers after straining from workouts, sickness, and other stressors.
Luckily, most Fitbits track HRV daily (overnight), showcase trends upwards or downwards over time, and help you get a quick snapshot of your overall well-being and how much stress your body is under.
In a hurry?
If time is short and you don’t need a thorough step-by-step, follow these quick instructions and check out your HRV metrics from your Fitbit!
- In the Fitbit app, open the Today tab and tap Health Metrics. Scroll down to the section Heart rate variability (HRV.)
What is heart rate variability?
In simple terms, your heart rate variability (HRV) is the time in milliseconds between each heartbeat.
Our hearts do not steadily beat like a metronome.
Instead, our autonomic nervous system varies the timing between each beat, balancing between its two branches: the sympathetic (fight-or-flight) and parasympathetic (rest-and-digest).
Your HRV is personal
Everyone’s HRV is different and depends on various factors, including age, gender, hormone levels, sleep quality, physical fitness, diet and nutrition, lifestyle choices (such as caffeine, alcohol, and drug use), and genetics.
So, don’t compare your HRV to others’ HRV!
A normal HRV can fall anywhere from below 20 to over 200 milliseconds between beats. Because there is no standard HRV, you need to look and compare your HRV to yourself and not others.
That’s why knowing your baseline HRV is so important and then looking at the variations (higher or lower) based on that baseline. In general:
• A higher HRV (relative to your baseline) is associated with greater parasympathetic responses (rest-and-digest.) A higher HRV points to greater cardiovascular fitness, better resilience to stress, quicker recovery, and more restful sleep.
• A lower HRV (relative to your baseline) is associated with greater sympathetic responses (fight-or-flight.) Lower HRV points to stress (good and bad), overtraining, illness, and even depression or anxiety.
For more information on Fitbit and HRV ranges by age and gender, see this recent clinical study on Fitbits.
How Fitbit tracks your HRV
Fitbits currently track your HRV when you sleep and do not offer a way to track HRV during the day.
Fitbit chooses to track HRV overnight because, during the daytime, many other outside factors influence HRV, including workouts and even things like how much caffeine you drink.
Additionally, measuring your HRV when you are relaxed and sleeping tends to show a higher and more accurate measure of your body’s recovery from the day’s activities, stress, and other factors.
So you must wear your Fitbit to bed to track HRV. Additionally, HRV tracking only kicks in when you sleep for at least 3 hours.
How to check your HRV (heart rate variability) on Fitbit
The Health Metrics dashboard that includes HRV information is available with Fitbit Charge 2+, Inspire HR+, Alta HR, Ionic, Versa Series, and Sense devices only.
To gather this data, you must wear your device for at least a full day, including sleeping at night. Fitbit records your HRV during the night only, when sleeping for a minimum of 3 hours.
- Open the Fitbit app.
- Tap the Today tab.
- Choose the Health Metrics tile.
- Scroll down to the section Heart rate variability (HRV.)
- Review the graph of your nightly average heart rate variability (by milliseconds.)
- Tap LEARN MORE to see additional details.
If the graph shows no recent data, wear your Fitbit when you sleep for several nights, making sure you sleep at least 3 hours or more.
Concerned about your HRV numbers from your Fitbit?
If you see daily fluctuations in your HRV, this is usually normal and expected. So keep wearing your Fitbit overnight and look for overall trends upwards or downwards.
- Seeing an upward trend? That’s awesome and a good indication that your heart health and overall resilience are improving.
- Seeing a downward trend? That might be a concern. Look for things that might have influenced that trend, such as drinking or taking recreational drugs, a new medication, a recent illness, a traumatic or stressful life event, and so forth.
- Getting a sudden and significant drop? If your HRV suddenly plummets, it’s possible that your body is experiencing strain, overtraining, stress, or that you might have a potential illness or injury.
If you are worried about a declining HRV, reach out to your healthcare provider for follow-up and let them know your Fitbit has recorded some concerning HRV data.
Remember that while your Fitbit offers you guidance, it is not a substitute for medical care and approved health diagnostics.
Not getting accurate HRV on your Fitbit?
To calculate your HRV, Fitbit currently uses its optical sensor, not an ECG, to calculate your HRV.
To get good readings, you need to wear your Fitbit snuggly, so its sensors are in direct contact with your skin. Additionally, wearing the watch a few inches above your wrist bone tends to give better readings.
If you wear your Fitbit loosely, with a little room between the watch and skin, you won’t get good heart rate and HRV recordings.
Finally, remember that your Fitbit is not a diagnostic tool, it’s rather a guide. Rather than focus on a number, look a your baseline and identify trends–downwards or upwards.
Looking for daytime and nighttime HRV measurements?
Unfortunately, Fitbits, along with many other wearables, do not track daytime HRV.
If you want to track both, consider purchasing a Whoop Strap, which captures your HRV while awake and asleep.
Want to improve your HRV?
Yes, you can increase HRV no matter your age! Be patient and keep a routine; your HRV won’t improve overnight–be in it for the long haul.
Stop smoking or using tobacco products. Okay, we all know how detrimental smoking is to your health. Among other negative outcomes, smoking adversely affects your heart rate variability (HRV), suggesting dysregulation of cardiac autonomic function. On the other hand, once you stop smoking, you see improved cardiac regulation.
So, if you consume these products, work with your doctor to be nicotine and smoke-free.
Exercise regularly. If you currently don’t get a lot of exercise, try getting out and about and do a little cardio workout. You don’t have to train at a gym, find something that you enjoy and try to incorporate that into your everyday routine.
Allow time for recovery. Traning is great. Overtraining is not! Working out intensely every day without allowing your body to recover is a big no-no. So take the time to rest and recover.
Maintain a healthy diet. Studies show that nutrition matters with HRV. Poor nutrition, especially food with high amounts of saturated or trans-fat, or high glycaemic carbohydrates, reduces HRV.
When you eat also matters. Eating late at night or just before you sleep tends to lower your HRV. So skip the late night snacks!
Hydrate. Our bodies need water to work. When you’re sufficiently hydrated, your blood easily circulates to deliver essential oxygen and nutrients. Aim to drink about one ounce of water per pound of body weight each day.
Get a good night’s sleep. Our bodies do most of their repair and recovery work when we are at rest and sleeping. Recent studies show that poor sleep quality adversely impacts your HRV.
So get into a good sleep habit by focusing on the quality of your sleep–that means limiting distractions! We recommend using bedtime mode or sleep mode on your phones and smartwatches to limit any interruptions!
Limit or abstain from alcohol. Recent studies indicate that alcohol consumption negatively impacts HRV. Alcohol intake was associated with an increase in sympathetic regulation and a decrease in parasympathetic regulation. Drinking alcohol also prevented sufficient recovery.