What does heart rate variability tell us about stress?

Heart rate variability can be a valuable indicator of how well your body responds to stress.

Most of us can recognize common signs of stress, such as difficulty concentrating or trouble sleeping. But did you know there is a subtle yet important measure known as heart rate variability that can provide insight into how well your body handles stress? Not only is there a link between heart rate variability and stress, but it can help assess your overall health.

What is heart rate variability and what does it measure?

Heart rate variability (HRV) measures the variation in time between heartbeats. It indicates how well the body balances stress and relaxation. The autonomic nervous system (ANS) regulates HRV through two branches: the sympathetic nervous system, which activates the "fight-or-flight" response, and the parasympathetic nervous system, which promotes "rest and digest."

Lower HRV means less time between heartbeats and often signals increased sympathetic activity. This suggests the body is in a prolonged "fight-or-flight" state. When HRV stays low, heart rate and blood pressure remain elevated, and the adrenal glands continue releasing adrenaline, keeping the body on high alert.

Higher HRV means more time between heartbeats, indicating stronger parasympathetic activity. This reflects a relaxed state where heart rate and blood pressure slow down. A high HRV also helps the body adapt to stress more efficiently and recover faster from physical and mental strain.

How to use HRV to assess stress and overall health

HRV varies from person to person and can be influenced by several factors, including:

• Age: HRV naturally decreases with age.
• Lifestyle habits: Poor sleep, smoking and excess weight can lower HRV.
• Medical conditions: Heart disease, diabetes and other chronic illnesses may affect HRV.
• Environmental factors: Stress, diet and daily activity levels all play a role.

The most accurate method to measure HRV is with an electrocardiogram (ECG). However, your doctor may also provide a monitor to track your HRV at home over a longer period, giving them more data to analyze. Certain wearable devices can measure HRV as well, though they are usually less accurate than a continuous ECG.

Measuring your HRV regularly can show how well you're handling stress and whether you're maintaining healthy habits in your daily life. Consistently high stress levels can negatively impact both mental and physical well-being. Too much stress can contribute to memory problems, heart issues and increased inflammation, which has been linked to diseases such as cancer and diabetes.

Normal HRV can vary depending on age and lifestyle factors. HRV typically decreases as people age. A normal HRV for someone in their teens to early 20s can average between 55 and 100 milliseconds. At the other end of the age spectrum, people 60 and older can see average HRVs of 25 to 45 milliseconds.

If your HRV remains low, it may indicate difficulty adapting to stressful situations. People with higher HRV tend to experience less stress and greater overall well-being than those with low HRV.

Unhealthy habits, such as poor sleep, smoking and excess body weight, can also lower HRV. By knowing your average HRV, you can track how it changes as you adopt healthier habits, such as regular sleep and physical activity.

How to improve HRV with stress-reducing techniques

Relaxation techniques help lower blood pressure and slow heart rate, which can raise HRV and improve the body's ability to handle stress. Managing both HRV and stress together can support overall health.

Some effective ways to improve HRV include:

• Breathing exercises: Techniques such as diaphragmatic breathing or box breathing can slow your heart rate and improve HRV. A slower heart rate allows for greater time between beats.
• Exercise: Regular physical activity not only benefits overall health, but also helps lower stress hormones, including cortisol.
• Progressive relaxation: Also called progressive muscle relaxation, this technique involves tensing and then releasing different muscle groups, usually starting at the toes and working up to the face. It helps you recognize the difference between tension and relaxation.
• Sleep: Getting enough rest reduces cortisol levels and can lower stress. People who don't get enough sleep are more likely to experience frequent stress compared to those who sleep well.
• Visualization: Also known as guided imagery, this technique uses positive mental images to promote relaxation. Focusing on peaceful settings can help reduce stress and anxiety.

Stress can sometimes feel unavoidable, but there are ways to manage it while improving HRV and overall health. Tracking HRV can help you see where adjustments — like better sleep or more physical activity — might be needed.