How Saunas Affect Heart Rate Variability (HRV)

What is HRV?

Heart Rate Variability (HRV) measures the variation in time between each of your heartbeats. Improving it is one of the lesser-known secrets of leading a richer life.  

You may already track your heart rate (for example, during or after exercising) and strive for an ideal number of beats per minute. But whether your heart rate is resting or elevated, the intervals between these beats are not consistent. One interval may be 0.9 seconds, another 1.1 seconds. And that’s a good thing – the more variety you have, the better you are at responding to the needs of the moment.  

The science behind this involves two complementary branches of your autonomic nervous system: 

• Your sympathetic nervous system (often called “fight or flight”) is always on alert for sudden changes in your environment and tells your heart to beat faster to supply blood to muscles that may be called into action. 
• Your parasympathetic nervous system (often called “rest and digest”) prioritizes the ongoing health of your internal organs and tells your heart to slow down. 

A high HRV score means your heart is doing a little of both in response – a sign that you can quickly commit to one mode or the other as needed.  

What is a good HRV score? 

An HRV score is measured in milliseconds and calculated by specialized equipment that includes many wearable monitors and (for true precision) an EKG from a medical professional.  

These resting HRV scores are considered normal (and the high end is better): 

• All adults: 19-75 milliseconds (ms) 
• Young adults (20s): 55-105 ms 
• Older adults (60s): 25-45 ms  
• Athletes and very fit adults: up to 100+ ms 

As with other health and longevity tools, it’s a good idea to compare yourself to your own baseline and focus on besting that. HRV scores typically drop with age but can be lifted by lifestyle enhancements like a healthy diet, regular exercise, proper hydration, and consistent sleep. Science points to infrared sauna as another technique to add to this wellness repertoire.

How can saunas affect HRV?

Studies show that a single infrared sauna experience favorably modulates your autonomic nervous system.

This means that the exposure to high temperatures triggers your sympathetic system and raises your heart rate. With that comes a drop in HRV: the intervals between your heartbeats become less varied because “fight or flight” defenses are making more demands than “rest and digest.” Similar to a vigorous workout, your body is choosing the state of high alert. 

While more studies are needed, research is showing that this positive impact on HRV may be a long-term change: 

• 30 patients with chronic heart failure took part in a two-week program of daily 15-minute infrared sauna sessions and saw improved HRV over a non-treated group. 
• 26 patients with allergic rhinitis used an infrared sauna three days a week for six weeks and achieved significantly higher HRV scores over a non-treated group. 

An ongoing HRV boost may be one explanation for the many proven cardiac benefits of infrared saunaing.  

Does saunaing lower or raise HRV? 

HRV measures the variation in time between heart beats. A higher HRV score means there is more fluctuation between those times, which indicates a good balance between your body’s response to your sympathetic nervous system (“fight or flight”) and parasympathetic system (“rest and digest.”). Your heart is prepared to beat faster in times of high alert and easily slow down to promote the ongoing health of your body.  

The high temperatures of an infrared sauna causes a drop in HRV during your session because your sympathetic system becomes dominant. But within five to 30 minutes afterwards, HRV returns to its previous level – or improves upon it – as your parasympathetic system makes a comeback. Research suggest this “autonomic nervous system modulation” may have ongoing benefits to your HRV and raise your score, which helps prevent high blood pressure, cardiovascular disease, sudden cardiac death, cardiac arrhythmias, and other conditions that keep you from feeling better so you can do more of what you love. 

Raise your HRV with Sunlighten 

Studies show that both infrared sauna therapy and traditional saunas have a favorable effect on HRV. But infrared light penetrates the skin and tissues, promoting healing from within – which doesn’t require the high temperatures of traditional saunas that many people find less comfortable.

As the leader in light science, Sunlighten is a powerful partner to have on your wellness journey. We combine patented technology, exceptional product quality, and 25 years of science-backed innovation to help you boost HRV and meet other wellness and longevity goals in comfort and style.