Heart Rate Variability (HRV) is a measurement of your heart’s electrical activity during sleep. HRV measures the variations in the amount of time it takes for your heart beats to beat at different rates. These variations are called “races” and they indicate if you’re awake or asleep. They may also be used to determine whether you’ve had enough rest or not.
What Is Heart Rate Variability?
Your heart beats approximately 60 times per minute. Your heart rate varies from one heartbeat to another, but it doesn’t vary much when you’re sleeping. You might think that your heart would remain relatively steady throughout the night, but it does fluctuate slightly due to factors such as stress and fatigue. When you wake up, your heart will return back to its original rhythm again.
The variation in your heart rate is known as your “variability.” Your heart rate variability is measured with a device called an electrocardiogram (ECG). An ECG consists of two electrodes placed against the skin. One electrode measures the electrical activity of the heart while the other measures blood flow through arteries and veins. A high level of variability indicates that you’re awake, while low levels indicate that you’re asleep.
How Does Heart Rate Variability Measurement Work?
Heart rate variability (HRV) is a measure of how much your heart rate changes over a set amount of time. HRV may differ among people and may change during the day. These changes can be caused by physical factors such as sleep and exercise or by emotional changes such as stress or anger. Having a higher HRV generally indicates that you are more fit, but it can also indicate something else.
The amount of time between heartbeats is called the “RR interval.” There are two primary ways to measure HRV: time domain HRV and frequency domain HRV. Time domain HRV measures the actual length of the intervals between heart beats. Frequency domain HRV assigns a value to each beat based on its relationship to previous and subsequent beats. The system classifies beats into categories such as very rare, rare, occasional, frequent, and common.
Does HRV Really Work?
HRV is a reliable indicator of certain health conditions. It has been shown to be a more accurate measurement of the body’s stress response than traditional heart rate. People who have high levels of stress, such as those with post-traumatic stress disorder (PTSD), often have higher levels of stress-hormones. These hormones can cause the body’s sympathetic nervous system to become overworked. As a result, the body’s natural ability to lower stress is reduced.
The sympathetic nervous system controls the fight or flight response. When you are faced with a potentially dangerous situation, your body prepares itself to either face the danger or run away from it. This response is important for your survival, but constant activation of the sympathetic nervous system can lead to high blood pressure and increase your risk of heart disease and stroke.
HRV can be an early indicator of heart disease. Having a low HRV means that your body is under constant stress. A consistently high HRV means that your body is prepared for any dangers and is in a state of relaxation.
How Do I Increase My HRV?
There are a variety of things you can do to increase your HRV:
Many forms of meditation have been shown to reduce levels of the stress hormone cortisol.
Sources & references used in this article:
Heart rate variability: The new science of recovery by C Marker – 2017 – breakingmuscle.com
Coarse-graining spectral analysis: new method for studying heart rate variability by Y Yamamoto, RL Hughson – Journal of Applied Physiology, 1991 – journals.physiology.org
Effects of propranolol on recovery of heart rate variability following acute myocardial infarction and relation to outcome in the Beta-Blocker Heart Attack Trial by R Lampert, JR Ickovics, CJ Viscoli, RI Horwitz… – The American journal of …, 2003 – Elsevier
Cardiac autonomic responses during exercise and post-exercise recovery using heart rate variability and systolic time intervals—a review by S Michael, KS Graham, GM Davis – Frontiers in physiology, 2017 – frontiersin.org
Heart rate variability–a historical perspective by GE Billman – Frontiers in physiology, 2011 – frontiersin.org