What Is Relaxation, and How Is It Measured?

In plain words

"Relaxation" can mean feeling calm, having less muscle tension, a body response that is the opposite of the stress response, or all three. In research, which one is being measured matters. This page explains the main ways it is measured so you can read claims about breathing and relaxation more carefully. For practices, see relaxation techniques at a glance and the relaxation response and stress physiology.

What NCCIH calls the relaxation response

NCCIH describes relaxation techniques as practices to help bring about the body's "relaxation response," characterized by slower breathing, lower blood pressure and a reduced heart rate. [1] It says the relaxation response is the opposite of the stress response. [1] This is a description of a body state, not a promise about health. Breathing exercises appear on NCCIH's list; the example given is slow, deep breaths, also called diaphragmatic breathing. [1]

Two ways to measure it

Examples from the research

• A questionnaire. A Japanese team developed a short self-report measure of relaxation effects. Statistical analysis found three factors: physiological tension, psychological relaxation and anxiety. [2] In a subgroup of 24 people, a heart-rate-variability measure taken during relaxation instruction correlated with the physiological tension scores. [2] That suggests self-report and body signals can line up, at least in a small group (abstract read; the paper is in Japanese).
• Feeling and body do not always match. In a study of highly and less hypnotizable people during simple relaxation, both groups reported similar subjective relaxation, yet their heart-rate-variability patterns differed. [3] The authors concluded that relaxation cannot be defined solely on cardiovascular parameters. [3]
• Slow breathing in healthy people. A systematic review of 15 studies found slow breathing was linked with higher heart-rate variability and with psychological changes such as increased relaxation and comfort and reduced anxiety symptoms. [4]

What this means for breathing claims

• A rise in heart-rate variability after slow breathing is a physiological finding. It is not by itself a health outcome. See vagal tone, heart-rate variability and respiratory sinus arrhythmia.
• A feeling of calm is real and worthwhile, but it is a self-reported outcome and may be influenced by expectations. Trials cannot hide from participants that they are practicing.
• Different studies use different measures, so a "relaxation" result in one paper may not mean the same thing in another.
• Proper evidence not found (we looked in NCCIH pages and PubMed searches for measurement of relaxation) for a single agreed standard test of "relaxation" that works for everyone. Wearables that give a "relaxation" or "stress" score are covered by the Biohacking library; see breathing and muscle-tension biofeedback.

Where to go next

Start with gentle breathing and relaxation practices, or read the breathing and relaxation basics.