Using Biofeedback When Practicing Lowering the Flight or Fight Response

Joseph Strayhorn, M.D.

Question: What do we mean by the “flight or fight response”?

Answer: Our bodies react to threats by activating the “sympathetic nervous system.” I prefer to speak of the flight or fight system, rather than the sympathetic system, because what goes on doesn’t involve sympathy! When we perceive that there is danger, our bodies get ready for lots of exertion of the muscles. Our adrenal glands release adrenaline, also known as epinephrine; this is a hormone that is meant to increase energy. Norepinephrine, an important neurotransmitter, is also involved in the response. (A neurotransmitter is a chemical that lets nerve impulses go from one nerve cell to the next.) The activation of this system causes:

our hearts to beat faster

our muscle tone to increase

some of the little blood vessels to constrict

resulting in blood pressure increase

also resulting in colder hands and feet

increased sweating

increased rate of breathing

greater feelings of vigilance and activation – feeling “hyped up”

resulting in a more intense experience of fear

or a more intense experience of anger

and a bunch of other effects.

Question: Is the flight or fight response “bad?”

Answer: It can be very useful, and even life-saving. If you need to run away from a dangerous person, the adrenaline you pump out can let you get away! However, often the flight or fight response is just what we don’t need. When someone does something that is mildly frustrating to us, and we get the flight or fight response of a level that would be appropriate for a life-or-death fight, that’s too much – we need some “anger control.” Or when some not very dangerous situation happens, but our bodies react as if we need to run to save our lives, we need to reduce our anxiety.

Question: Can people learn to turn up or down their flight or fight responses?

Answer: People used to think that the action of this part of our nervous system was out of our control. But lots of experiments have shown that we can learn to have control over our flight or fight responses. Learning to turn down this response can have major helpful effects for anxiety reduction and anger control. Turning down the flight or fight response is a large part of what we mean by the word “relaxing.” We can learn to relax more effectively.

Question: What is biofeedback?

Answer: It’s measuring something that is going on in our bodies, so that our getting the feedback of what is going on will help us learn to control what’s going on. What we’re talking about in this handout is simply using biofeedback as a way of measuring how much we are relaxing.

Question: What is measured in the biofeedback we’re talking about here?

Answer: In this handout, we’re talking about things that go up or down with the flight or fight response, and go in the opposite direction when we relax. We’re talking about 1) heart rate, 2) fingertip temperature, 3) the amount of sweat at the fingertips, and 4) muscle tension. We are mainly focusing on the first two of these, because they can be measured in very inexpensive and easy ways.

With greater relaxation, 1) heart rate goes down, 2) fingertip temperature goes up, 3) the “conductance” of the skin goes down because the sweat goes down, and 4) muscle tension goes down. In this handout I’ll talk about the first two of these, because they can be measured very inexpensively and easily.

Question: How is measuring supposed to help people learn to relax?

Answer: Imagine that you were trying to learn to shoot basketballs through a hoop, but you couldn’t see or hear whether the balls went into the hoop or not. You wouldn’t know how to adjust your efforts to meet your goal. You wouldn’t know whether to throw the ball harder or softer, on a higher or lower arc, or what. But if you take away the blindfold and the ear plugs, you can see the results of your efforts, and gradually learn to make more and more of your shots.

In the same way, biofeedback gives you an indication of how successfully you are relaxing. If you try some method of relaxing and you find that it lowers your heart rate and raises your fingertip temperature more than some other method, that’s a piece of evidence to use that method more.

Question: How do you measure your heart rate, otherwise known as pulse rate?

Answer: The lowest tech method is to put your fingers on your wrist, find your pulse, use a watch to count your pulse for a certain time, and use some arithmetic to find the beats per minute. There are a number of watches on the market that are supposed to give a fairly accurate measure of your heart rate. But the device I recommend is a “pulse oximeter.” You can get these inexpensively. You stick your finger into it (all the way), push a button, and wait for the heart rate to display on the screen. As the heart rate speeds up or slows down, the number on the display changes. If you relax, and you see the number going down, that’s a piece of evidence that you’re lowering your flight or fight response.

There are two numbers displayed on a pulse oximeter. The one we’re interested in now is the one labeled “PR bpm.” This stands for “pulse rate, beats per minute.” The other number is labeled “SpO2 %.” This stands for “saturation of peripheral oxygen, per cent.” This has to do with how much oxygen is in your blood cells. This doesn’t have to do with the flight or fight response. (People who have pneumonia, or a bad asthma attack, or heart failure, can have their “SpO2 %” lowered.)

Question: What’s a way of using heart rate when practicing relaxation?

Answer: You can just put the pulse oximeter on and give a few seconds to let it settle out to a fairly stable number measuring your heart rate. (It sometimes jumps around a bit when you first turn it on.) Then you relax for however long you want. A minute or two is often enough to see a pretty big difference in heart rate. You can close your eyes while relaxing, and just look at the heart rate at the end of the time. Or you can watch the heart rate number the whole time. You just use the feedback to help you know what effect your relaxation technique is having on your body.

Question: How do you measure fingertip temperature?

Answer: There are some thermometers on the market called “stress thermometer.” There are some even less expensive thermometers meant to measure the temperature for aquariums, that give similar numbers. For these there is a probe, meaning a wire coming out from the thermometer, and you hold it either between the thumb and a finger (if the probe is small) or with the thumb and two fingers (if the probe is a little bigger). You get accurate results when the probe has had time to get to be the same temperature as your fingers, and this takes a little longer than the heart rate monitor takes to get to an accurate number. I’d give it half a minute before you consider the number meaningful.

Question: What’s a way of using fingertip temperature when practicing relaxation?

Answer: You can just note what your fingertip temperature is, after giving about half a minute for the temperature to settle out. Then you use a relaxation technique. As with heart rate, you can either watch the temperature the whole time, or you can just look at it at the end of your relaxation time. Fingertip temperature fluctuates lots more slowly than heart rate does. Nonetheless, a couple of minutes of relaxation can sometimes result in fairly significant changes in fingertip temperature.

Question: What if it’s very cold or hot in the room where you’re using fingertip temperature to measure relaxation?

Answer: If you’re feeling cold, you’re probably going to get low fingertip temperatures no matter how relaxed you get, and if you’re feeling very hot, you’re probably going to get high temperatures no matter how aroused you get. One source said that to use fingertip temperature as an accurate measure of the flight or fight response versus relaxation, the room temperature should be between 70 and 74 degrees Fahrenheit. If it’s a little lower, I think you can still get away with using temperature biofeedback if you have a warm sweater or coat on and you don’t feel chilly.

Question: What are some ways of relaxing that people have used, along with biofeedback?

Answer: These are discussed in greater detail elsewhere. Some of these are: muscle relaxation, slow breathing (for example, 5 seconds in and 5 seconds out), use of a “mantra” or word that you repeat to yourself, visualizing relaxing places, visualizing kind acts between people, repeating good-will wishes toward one person after another (a.k.a. the loving kindness meditation), and others. One of the first and most widely researched is relaxation of the muscles.

Question: What are typical numbers for heart rate and fingertip temperature, before and after relaxation?

Answer: These vary widely from person to person. The best answer is found by experimenting around. But for adults, heart rates near 100 often signify that the person is flight-or-fight ready, and heart rates closer to 60 often signify that the person is relaxed. But if the heart rate goes down even by 5 beats per minute from wherever it started, that can be a sign that relaxation is working.

For fingertip temperature, anything over 95 degrees Fahrenheit is about as warm as you’re going to get, and in a 70 degree room it usually accompanies fairly high relaxation. Anything over 90 is fairly relaxed. People can start out with fingertip temperatures in the 70s or sometimes even lower; more common is to start out in the 80s.

Again, the numbers need to be individualized for any given individual!

Question: How do you use biofeedback while “desensitizing” yourself to a situation that triggers anger or fear?

Answer: You measure your heart rate or fingertip temperature while speaking aloud, reading aloud, or just imagining, a fantasy rehearsal of handling that situation. You will want to imagine handling the situation well, handling it as you want to be able to handle it. You notice what happens to your heart rate and/or fingertip temperature before, during, and after the fantasy rehearsal. If you notice that you’re getting some flight-or-fight reaction, you celebrate that you are imagining proficiently! If over time the flight-or-fight reaction goes down, you celebrate that you are learning to keep cool in this situation!

Question: What about the feedback of how relaxed, versus how scared or angry I feel, just looking at my own emotions?

Answer: This is very important feedback, perhaps more important than what the heart rate or temperature is telling you! Plus, it costs nothing to measure! Some people are more “in touch with their feelings” than others. Sometimes monitoring heart rate or fingertip temperature can even help people to become more “in touch.” For anger and fear, people have used the SUD level as a way of just monitoring their own emotions. SUD stands for “subjective units of distress” – how unpleasant is the emotional reaction? 0 means no distress (or disturbance, or discomfort) at all, and 10 or 100 means the maximum possible bad feeling.

The SUD level is related to, but different from, the level of flight or fight response, or sympathetic activation. Having a high level of arousal can be pleasant – for example, when people have fun riding roller coasters, or seeing scary movies, or competing in athletics. The SUD level, by contrast is unpleasant, by definition. You can of course rate your level of arousal on a 0 to 10 scale also, where 10 is super energized, and 0 is super relaxed.

Question: If I try a relaxation method, and my heart rate or fingertip temperature doesn’t do anything, or if it even moves in the direction of greater arousal and activation, does that mean that the relaxation method isn’t a good one for me?

Answer: No. You sometimes have to practice and fiddle around with the relaxation technique for a while before you get the hang of it and can use it effectively.

Question: What handout on this website would you recommend reading before doing a lot of work on biofeedback?

Answer: I recommend checking out the one on muscle relaxation, and also the one entitled Relaxation Methods.