SlowpulseSearch for HRV by age and you will find neat tables: a row per decade, a tidy range in each. They look authoritative. They are mostly reproductions of each other, and the research they claim to rest on does not say what they suggest it says.
What the largest review of normal values concluded
The systematic review that pooled 44 studies and 21,438 adults set out to establish normal short-term HRV values. Having done so, its authors identified the need for large-scale population studies covering the full age spectrum — that is, they concluded such data was still missing, not that they had produced it.
An age-banded chart presented as settled fact is therefore claiming a precision the literature does not currently have. We are not going to print one here and pretend otherwise.
Editorial note — The age trend is sourced below. A per-decade numeric table is not, and we will not publish one until a single named, age-stratified dataset supports it — an average of other blog posts is not a source.
What can reasonably be said
The direction is not in doubt. A 2024 review of the factors influencing HRV states that HRV is highest in young adulthood and decreases nonlinearly with age. So yes — HRV does tend to fall as you get older.
That word nonlinearly is doing a lot of work, and it is precisely what a tidy per-decade table throws away. A trend that bends is not a trend you can slice into equal bands and read off. What is established is the shape of the curve; what is not established is a per-decade range narrow enough to tell one individual whether their own reading is fine.
The same review lists a long queue of other things that move HRV: time of day, sex, body composition, smoking, alcohol, heat, noise, shift work and training load. Any age band you look up is an average across people who differed on all of those.
Even if such a table existed, it would run into the problem from the previous page: healthy adults in that review spanned 32–93 ms on SDNN. Slice a range that wide by decade and the bands still overlap heavily. Your decade would not tell you much about you.
The comparison that does work
The review puts it plainly: comparisons within one person are usually uncomplicated, while confounders are exactly what get in the way when comparing between people.
Comparing yourself to a forty-year-old average asks whether you resemble a statistical composite. Comparing yourself to your own two-week baseline asks whether something has changed. Only the second question has an answer you can act on, and only the second one accounts for the fact that your normal is yours.
This also sidesteps the measurement problem entirely. If every reading comes from the same watch, in the same way, night after night, then the comparison is like-for-like even if the absolute number would not match anyone else's setup.
Sources
- Sammito, Thielmann & Böckelmann (2024) — Update: factors influencing heart rate variability, a narrative review, Frontiers in Physiology 15:1430458
- Nunan, Sandercock & Brodie (2010) — systematic review of 44 studies, 21,438 adults
Related
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