What Is a Good HRV? Normal Heart Rate Variability by Age

A good HRV is one that is normal for you: steady or slowly rising over the weeks, not one magic number. For context, healthy adults resting for five minutes in lab studies average an RMSSD (a standard HRV measure) of about 42 milliseconds, and typical values roughly halve between your late 20s and your late 50s. Your own 7-day average, measured the same way each time, tells you far more than any chart.

Training by heart rate? Find your aerobic training range with our free Zone 2 heart rate calculator.

Sleep is one of the HRV levers you control, so a good first step is to find your ideal bedtime with our free sleep calculator and sleep score.

What is heart rate variability (HRV)?

Heart rate variability is the small, constant change in the time between one heartbeat and the next. Even at a steady 60 beats per minute, your heart does not beat exactly once a second. One gap might be 0.95 seconds, the next 1.05 seconds. As one major review puts it, “a healthy heart is not a metronome” (1).

Those tiny shifts come from your autonomic nervous system, which runs your heart, breathing and digestion on autopilot. It has two branches:

• Sympathetic (“fight or flight”): speeds the heart up and readies you for action.
• Parasympathetic (“rest and digest”): works mainly through the vagus nerve, slows the heart and lets it speed up and slow down with each breath (1).

When the rest-and-digest side has the upper hand, the gaps between beats vary more and HRV goes up. When you are stressed, short on sleep, unwell or have been drinking, the balance tips toward fight or flight and HRV tends to fall (1).

What is a good HRV?

There is no single good number, for three reasons: HRV drops with age, it depends on which HRV measure you use, and it changes with how and when it is measured (1).

The best starting point is a 2010 systematic review of 44 studies covering 21,438 healthy adults. For short resting recordings (usually about 5 minutes on an ECG), average RMSSD was 42 ms, with a standard deviation of 15 ms, and the average values reported by individual studies ranged from 19 to 75 ms. A second measure, SDNN, averaged 50 ms (2).

The same review found huge differences between healthy people, up to 260,000% for some measures, mostly the frequency-based ones (2). A friend’s HRV of 80 does not make your 35 “bad.”

In practice, a good HRV is one that:

• sits within the typical range for your age (see the chart below),
• stays fairly stable from week to week, and
• dips only for a day or two after obvious stressors, like a late night or a few drinks.

Normal HRV by age: what the research shows

The clearest age data come from a German population study of 1,906 healthy adults. The researchers excluded anyone with heart disease, high blood pressure, diabetes or heart-affecting medicines, then took a 5-minute ECG while each person lay down after 5 to 10 minutes of rest (3).

Source: Voss et al. 2015 (3). 5-minute resting ECG, lying down. The number after ± is one standard deviation.

Three things stand out:

• The spread is wide. For a woman aged 25 to 34, anything from about 20 to 66 ms is within one standard deviation of average.
• RMSSD roughly halves from 25–34 to 55–64 in both women and men, then levels off. The 65–74 group was not significantly different from the 55–64 group (3).
• Women and men were not significantly different on RMSSD in any age group (3).

One caveat: this is a daytime 5-minute lab reading. The overnight number on your ring or watch is a different measurement and will not line up neatly with this chart (1).

Why your HRV number depends on the metric and the device

RMSSD vs SDNN

RMSSD looks at the change from one beat to the next. It is the main time-based measure of the rest-and-digest (vagal) side of your nervous system, and it is the number Oura, WHOOP, Garmin and Polar all report (1, 4).

SDNN is the overall spread of all your beat-to-beat gaps. Both branches of the nervous system feed into it, and it grows with the length of the recording, so a 24-hour SDNN and a 5-minute SDNN are not interchangeable (1).

In 24-hour heart recordings, an SDNN below 50 ms has been classed as unhealthy and above 100 ms as healthy (1). But healthy adults average about 50 ms on a 5-minute recording (2). Apply the 24-hour cut-offs to a short reading and you would wrongly flag many healthy people as unhealthy.

Every wearable calculates HRV differently

A 2025 validation study tested five popular devices against a chest-strap ECG in 13 healthy adults over 536 nights. All five report RMSSD, but each calculates it its own way (4):

• Oura (Gen 3 and Gen 4) and Garmin (Fenix 6): average 5-minute windows across the whole night.
• Polar (Grit X Pro): uses a 4-hour window after you fall asleep.
• WHOOP (4.0): uses a running average weighted toward your last deep-sleep stage.

Accuracy differed too. The Oura rings agreed most closely with the ECG (average error about 6 to 7%), WHOOP was moderate (about 8%), and the Garmin and Polar models trailed (about 11% and 16%) (4). It was a small study of specific models (the authors declared no competing interests), and newer models may differ.

The practical rule: compare yourself only with yourself, on the same device. If you switch devices, start a new baseline. If you are choosing one, our guide to the best fitness trackers for Zone 2 and VO2 max training is a good place to start.

Is low HRV bad for your health?

Across large groups of people, yes, low HRV is linked to higher risk. A meta-analysis of 8 studies with 21,988 people who had no known heart disease found that those with the lowest SDNN had about a 35% higher risk of a first cardiovascular event, fatal or non-fatal, than those with the highest. Overall, low HRV was tied to a 32 to 45% higher risk, depending on the measure, and each 1% rise in SDNN went with roughly 1% lower risk (5).

Reviews also link low HRV with depression, anxiety, inflammation, diabetes and higher overall mortality (1).

Two important limits:

• These are associations. Low HRV may be a marker of an underlying problem rather than its cause. They do not prove that nudging your wearable number up will, on its own, prevent heart disease.
• The studies used medical recordings, mostly SDNN, not overnight RMSSD from a consumer device (5).

And higher is not always better. Abnormal heart rhythms can produce high HRV readings, and when heart conduction problems raise HRV, that is linked to higher mortality, especially in older adults (1). Atrial fibrillation, an irregular heart rhythm, distorts HRV readings (4). HRV works best alongside your resting heart rate; see what is normal in our guide to a healthy resting heart rate.

What lowers HRV?

Alcohol

Alcohol has one of the clearest effects. A study of 4,098 Finnish employees compared each person’s nights with and without drinking. In the first three hours of sleep, RMSSD fell by an average of 2.0 ms after about one drink, 5.7 ms after about three, and 12.9 ms after about seven, while sleeping heart rate rose by 1.4, 4.0 and 8.7 beats per minute (6). (A “drink” in the study held 12 grams of alcohol.)

Even low intake had a measurable effect, being physically active did not protect against it, and the drop was larger in younger people (6). Disclosure: two of the authors worked for Firstbeat Technologies, a company that makes HRV-based analysis tools, and one for Nokia Technologies (6). For the full picture, read why a nightcap wrecks your sleep.

Sleep loss

A 2025 meta-analysis of 11 randomized trials (549 people) found that sleep deprivation significantly lowered RMSSD. The change in SDNN was not significant, and the studies varied a lot, from short nights to 24 hours without sleep (7).

Stress

A review of 37 studies found that psychological stress most often showed up as lower parasympathetic (rest-and-digest) activity in HRV (8). Those studies measured short-term reactions to stress, so they say more about a tough day than about years of chronic stress. Our guide on how to lower cortisol and stress naturally covers what helps.

Illness

Reviews tie both acute and chronic illness to autonomic imbalance, the pattern that low HRV reflects (1). If your HRV drops sharply for several days with no other explanation, coming down with something is one possibility.

Hard training (it is complicated)

It is tempting to read a falling HRV as a sign of overtraining. The evidence is mixed. A meta-analysis of endurance athletes found that resting HRV was largely unaffected by overreaching, the stage of too much training that hurts performance. Resting RMSSD even rose slightly, though the authors say study methods may explain part of this (9). So resting HRV alone is not a reliable overtraining alarm; how you feel and perform matter too.

How to improve HRV (what works over weeks)

Train regularly

A 2024 meta-analysis of 16 randomized trials (623 healthy adults) found that exercise programs of 4 weeks or longer raised both RMSSD and SDNN compared with no exercise. Programs averaged about 10 weeks, usually three sessions a week (10). The RMSSD gain was at least as large in people 40 and over, though the trials were small and varied, and they included strength and mixed programs as well as cardio (10). In endurance athletes, training that improved performance came with small rises in resting RMSSD (9).

You don’t need anything fancy: the trials used ordinary programs of cardio, strength work or both, about three times a week. For a starting point, our guides to Zone 2 cardio for longevity and how to improve your VO2 max show how to build a routine.

Practice slow breathing

A 2022 meta-analysis of 223 studies found that slow breathing raised vagal HRV during the session, right after it, and after programs lasting several sessions or more (11). HRV biofeedback typically guides people to breathe at about 4.5 to 7.5 breaths a minute (1). A simple version is a 5-second inhale and a 5-second exhale, which works out to 6 breaths a minute. Most of these studies (172 of 223) measured HRV during the breathing itself, so how much daily practice shifts your overnight wearable number is less certain.

Protect your sleep and drink less

The evidence that sleep loss lowers HRV is fairly consistent (7), and the same people showed higher HRV on their alcohol-free nights (6). Evidence that a regular sleep schedule by itself raises HRV is much thinner; we could not find good trials testing it directly. Still, it costs nothing to try.

What raises and lowers HRV at a glance

How to read your wearable’s HRV the right way

1. Measure the same way every time. Overnight readings are easiest. If you take a spot reading, do it at the same time each morning, in the same position, before you get up and start your day. Recording length, time of day and breathing pattern all change the result (1).
2. Breathe normally during spot checks. Paced breathing pushes most HRV measures higher than normal breathing, so a reading taken mid-breathing-exercise is not your baseline (1, 2).
3. Watch the 7-day average, not the daily number. In trained triathletes, averaging at least three valid readings a week gave nearly the same picture as all seven, while a single reading gave a much weaker signal (12).
4. Learn your normal range. After a few weeks, you will know your usual spread. One low day after a late night or a few drinks is expected. A drop that lasts a week or more, with no obvious cause, is a cue to rest, check your sleep, alcohol and stress, and watch for illness.
5. Don’t compare across people or devices. Different devices calculate HRV differently (4), and healthy people vary hugely (2).

When to see a doctor instead: if you have palpitations, a racing, pounding or irregular heartbeat, dizziness, fainting, chest pain or unusual breathlessness, see a doctor. HRV is not a test for heart rhythm problems, and conditions like atrial fibrillation distort the reading (4).

The bottom line: a good HRV is your own stable baseline, read the same way on the same device. Build it with regular exercise, enough sleep and less alcohol, and treat the number as a nudge, not a diagnosis. If you are shopping for a device that tracks overnight HRV, our fitness tracker roundup compares the main options. For more free health checks, browse all our health calculators and tools.

This article is for general information only and is not medical advice. Please read our medical disclaimer.

Sources

1. Shaffer F, Ginsberg JP. An Overview of Heart Rate Variability Metrics and Norms. Front Public Health. 2017;5:258. PubMed 29034226
2. Nunan D, Sandercock GR, Brodie DA. A quantitative systematic review of normal values for short-term heart rate variability in healthy adults. Pacing Clin Electrophysiol. 2010;33(11):1407-17. PubMed 20663071
3. Voss A, et al. Short-term heart rate variability: influence of gender and age in healthy subjects. PLoS One. 2015;10(3):e0118308. PubMed 25822720
4. Dial MB, et al. Validation of nocturnal resting heart rate and heart rate variability in consumer wearables. Physiol Rep. 2025;13(16):e70527. PubMed 40834291
5. Hillebrand S, et al. Heart rate variability and first cardiovascular event in populations without known cardiovascular disease: meta-analysis and dose-response meta-regression. Europace. 2013;15(5):742-9. PubMed 23370966
6. Pietilä J, et al. Acute Effect of Alcohol Intake on Cardiovascular Autonomic Regulation During the First Hours of Sleep in a Large Real-World Sample of Finnish Employees: Observational Study. JMIR Ment Health. 2018;5(1):e23. PubMed 29549064
7. Zhang S, et al. Effects of sleep deprivation on heart rate variability: a systematic review and meta-analysis. Front Neurol. 2025;16:1556784. PubMed 40895095
8. Kim HG, et al. Stress and Heart Rate Variability: A Meta-Analysis and Review of the Literature. Psychiatry Investig. 2018;15(3):235-245. PubMed 29486547
9. Bellenger CR, et al. Monitoring Athletic Training Status Through Autonomic Heart Rate Regulation: A Systematic Review and Meta-Analysis. Sports Med. 2016;46(10):1461-86. PubMed 26888648
10. Amekran Y, El Hangouche AJ. Effects of Exercise Training on Heart Rate Variability in Healthy Adults: A Systematic Review and Meta-analysis of Randomized Controlled Trials. Cureus. 2024;16(6):e62465. PubMed 39015867
11. Laborde S, et al. Effects of voluntary slow breathing on heart rate and heart rate variability: A systematic review and a meta-analysis. Neurosci Biobehav Rev. 2022;138:104711. PubMed 35623448
12. Plews DJ, et al. Monitoring training with heart rate-variability: how much compliance is needed for valid assessment? Int J Sports Physiol Perform. 2014;9(5):783-90. PubMed 24334285