The Science Of The StressEraser
Video: The Science of the StressEraser (7:37)
The short video presentation above explains the science behind the StressEraser in layman's terms. If you are interested in more scientific detail, a technically complete discussion is provided in the following text.
- The Balance of Your Nervous System
- Allostatic Load, Cumulative Effects of An Unbalanced System
- Measuring Relaxation, HRV, RSA and the Vagus Nerve
- Achieving Relaxation, Breathing and Focusing with the StressEraser
- Realtime Biofeedback, How the StressEraser Works
- Glossary of Acronyms
Part 1: The Balance of Your Nervous System
Your Autonomic Nervous System (ANS) controls functions in the body that normally occur unconsciously, such as heart rate, respiration rate and digestion. This system is responsible for keeping your body in a regulated, balanced state. This balance is created by the constant back and forth nature of the two primary branches of your ANS: the Sympathetic Nervous System (SNS) and the Parasympathetic Nervous System (PNS).
[Fig 1] [Fig 2]
Your SNS is involved in mobilization responses that enable "fight or flight" behaviors known as the stress response [Fig. 1]. Your PNS is involved in "rest and renew" behaviors that enable growth and restoration and are known as the relaxation response [Fig. 2]. Parasympathetic activity is regulated by your vagus nerve. The vagus nerve is the longest nerve in your body, extending from the brain stem to the base of the spine and to several organs and your heart. When the vagus nerve activates, the relaxation response is turned on. When the vagus nerve is inactive, the relaxation response is also inactive.
Typical functions of the SNS and PNS are detailed below:
Sympathetic Nervous System (SNS)
Your "fight or flight" or stress response can become activated by both major and minor stressors. Even states of excitement and emotions such as anger and fear activate the SNS. When your SNS is active it is characterized by:
- Increased heart rate
- Increased cardiac output
- Increased blood pressure
- Increased breathing rate
- Increased muscle contraction
- Constriction of capillaries under skin surface
- Increased secretion of adrenaline (epinephrine), noradrenaline (norepinephrine), and cortisol
- Increased brainwave activity
- Increased output of blood cholesterol
- Increased blood sugar
- Increased insulin levels
- Inhibited digestion and elimination
- Weakened the immune system (long-term)
- Inhibited of cell growth (long-term)
Parasympathetic Nervous System (PNS)
The primary pacifying nerve in your body, the vagus nerve, mediates the activity of the "rest and renew" or relaxation response. Overall, activation of the PNS promotes calming so you can recuperate from day-to-day stress, keeping the ANS in balance. When your PNS is active it is characterized by:
- Decreased heart rate
- Decreased cardiac output
- Decreased blood pressure
- Decreased breathing rate
- Released tension in tight muscles
- Dilated of blood vessels
- Released dopamine, serotonin, and acetylcholine
- Enhanced cognition
- Stabilized blood flow to muscles
- Increased oxygen to the blood
- Increased energy storage
- Enhanced digestion and elimination
- Strengthened immune system (long-term)
- Promotion of cell growth (long-term)
Ideally, the SNS and PNS operate in an evenly balanced manner, keeping your body in a state of physiological homeostasis [Fig. 3]. Although there are exceptions, in general when SNS activity increases, PNS activity decreases [Fig. 4]. In particular, when SNS activity increases, the activity of the vagus nerve decreases. SNS changes in your body are all extremely important, particularly if you are in a life threatening situation in which you have to fight or escape. When the stressful moment has passed, the PNS response kicks in to relax your body and return it to a balanced state.
Part 2: Allostatic Load, Cumulative Effects of An Unbalanced System
Unfortunately, our nervous systems have not yet adapted to the type of ongoing stress we face today. As you can imagine, there is a huge difference between the constant stress of 21st century life and our ancestor's sudden need to flee from danger. However, ongoing minor stresses such as traffic jams, work demands, problems at home, or financial concerns tend to build up. Emotions such as anger, fear and anxiety will cause your SNS to activate. As stress accumulates, your stress response remains active for longer than your body can handle. Your relaxation response, therefore, is less active, which throws your ANS out of balance.
Over time, repeated stressors and negative emotions have a cumulative wear and tear on the body that can lead to significant health problems. This is called "allostatic load". When you are healthy, your nervous system returns to normal functioning after a stressed situation by increasing vagus nerve activity. This helps the system to recover. When you are faced with stress on a daily basis, however, your stress response fails to shut off in a timely manner. Allostatic load leads to reduced activity of your vagus nerve. As a result, your system becomes hyperactive or begins to burn out.
Hyperactive stress responses cause your system to remain in fight-or-flight mode for an extended period of time. Burn-out inhibits both your SNS and PNS from activating. In both cases, your body becomes out of balance, making your system less flexible and less able to effectively adapt to external demands. Over time, allosatic load can cause significant health problems. There is now a large literature on the relationship to stress and disease. According to the American Institute of Stress, "it is hard to think of any disease in which stress cannot play an aggravating role." In fact, the Institute reports that up to 90% of doctors visits are stress related.
Part 3: Measuring Relaxation, HRV, RSA and the Vagus Nerve
The most accurate non-invasive measurement of autonomic regulation is Heart Rate Variability (HRV). HRV refers to beat-to-beat variation in your heart rate; this provides a window into the activity of your parasympathetic and sympathetic nerves.
Your heart rate is never constant. From one beat to the next, your heart rate is always rising and falling. This natural rise and fall is called Respiratory Sinus Arrhythmia (RSA). RSA is usually characterized by an increase in heart rate during inhalation and a decrease in heart rate during exhalation. Although this is called an "arrhythmia," it is not pathological; it is the natural fluxuation of your heart rate due to the constantly changing influence of your PNS on your heart.
RSA gives us a window into the ANS because it is a primary source of variability in heart rate. In general, the greater the "rhythmic" variation in heart rate, the better. For example: An at-rest heart rate that varies between 60 and 80 beats per minute (bpm) is preferable to an at-rest heart rate that varyies between 65 and 70 bpm. The greater your RSA, the more active your vagus nerve, and the more adaptive your nervous system is to the stressful demands of the environment.
Although there are numerous ways to measure HRV - and global measures of HRV provide a reasonable index of this nervous system adaptability - RSA is actually a more useful measurement. Since RSA provide a window into the regulating influence of the vagus nerve on the heart, it is also an excellent measure of resilience to stress (i.e., high-amplitude RSA) or vulnerability to stress (i.e., low-amplitude RSA).
Low-amplitude HRV and low-amplitude RSA have been found to be associated with the following (among others):
- Anxiety Disorders (i.e., PTSD, Generalized Anxiety Disorder, phobias)
- Chronic Obstructive Pulmonary Disease (COPD)
- Cardiac-related morbidity and mortality
- Coronary heart disease
- Depression (mixed findings)
- Chronic pain
- Headache (migraine and tension)
- Sedentary Lifestyle
- Substance Abuse
By contrast, high-amplitude HRV and high-amplitude RSA have been found to be associated with:
- Fetal Health
- Cardiac health
- Practicing meditation & yoga
- Emotional stability
- Increased social support
- Faster reaction time
- Increased attention
- Lower reactivity to stressors
- Overall health
Part 4: Achieving Relaxation, Breathing and Focusing with the StressEraser
As noted earlier, most of the actions of your ANS are involuntary. However, there is a wealth of literature on the voluntary manipulation of these systems to control the activation of your relaxation response. Perhaps the two most important methods of actively triggering your relaxation response are 1) learning to change your breathing and 2) learning to change your focus. By changing your breathing and your focus, you can increase the vagal influence on your heart—and therefore relax your body.
There is growing literature on the effects of these relaxation exercises on stress-related illnesses and performance. In particular, breathing slowly can activate the vagus nerve to help enhance autonomic control. However, slow breathing without physiological biofeedback—which provides the cues that you are doing it correctly—can actually be counter-productive because you are not breathing in sync with your nervous system.
For example, extending your exhale is generally a good thing. Slow breathing and extended exhales are integrated into most relaxation and meditation practices. But research reveals that extending your exhale TOO long is not good for your nervous system. The research also reveals that everyone has a unique breathing frequency that will maximize vagal activity. Moreover, a common complaint with unassisted breathing techniques is that your mind wanders shortly after beginning the exercise, which limits its physiological benefits.
The StressEraser is a tangible biofeedback device that was specifically designed to help you find the unique breathing pattern that maximizes RSA, maintains your focus, and most efficiently triggers increased vagal influences on your heart.
Greater variability, especially due to larger rhythmic changes associated with breathing, leads to a higher amplitude RSA wave - and therefore more parasympathetic (relaxation) activity. When there is greater parasympathetic tone, it supports health, growth, and restoration.
As you learn to find this breathing pattern, the StressEraser simultaneously guides you to focus your attention, a key aspect of proper physiological relaxation. The goal of this strategy is transform a heart rate pattern characterized by short, jagged RSA waves [Fig. 6.] into one characterized by large, smooth RSA waves [Fig. 7]. The StressEraser is the only portable HRV/RSA biofeedback device that allows you to follow and manipulate your RSA wave in real time. When used properly, it enhances the state of your nervous system, while inducing feelings of calm and relaxation.
Part 5: Realtime Biofeedback, How the StressEraser Works
The StressEraser measures your real-time beat-to-beat heart rate via an infrared finger sensor. The finger sensor has a built-in photoplethysmograph to identify the pulsation associated with each heart beat. The StressEraser accurately identifies the time of each pulse and calculates heart rate based on the time that has elapsed between the two most recent pulses. The StressEraser plots the up and down, wavelike movement [Fig. 8] and displays the pulse rate wave on the LCD screen.
By observing the RSA wave derived from your beat-to-beat pulse rate, the StressEraser provides a window into the activity of your vagus nerve [Fig 9].
The StressEraser then breaks down the RSA waves to analyze the frequency of each individual wave [Fig 10].
Once the frequency of the wave is computed, you receive immediate feedback on whether the wave was sufficiently long and smooth to receive credit. If you are breathing in your unique optimal pattern - and have a calm, neutral mind - you score 1 point for a large smooth wave, as marked by three vertical squares. The goal is to achieve this type of wave continuously. If the wave is long enough to indicate sufficient, but not optimal RSA, the user receives 1/2 point as marked by two vertical squares. If the wave is too short, the user receives no points, as marked by one square [Fig. 11]. (Note: Seniors and beginners can set a goal for continuous two-square waves.)
The minimum suggested session is 30 points (about 5-7 minutes) with a goal of 100 points per day (approximately 20 minutes).
To achieve continuous three-square waves, you are instructed to inhale until your heart rate peaks. This point is marked by a triangle. The triangle indicates the moment that a natural burst of vagal activity is about to begin, indicating your parasympathetic response. When the triangle appears, begin your exhale and shift your thoughts to a calming focus phrase (such as counting your exhale). Then, extend your exhale until the wave begins to rise again. At the end of your exhale, inhale until the next triangle appears. [See Fig. 12 for a description of the StressEraser interface].
Your optimal wave pattern is shown in Fig. 13. The slow breathing rate required to create this wave varies from person to person, but is usually somewhere between 4.5 and 7 breaths per minute. Your unique pattern is called your "resonant frequency." When you attain your own resonant frequency pattern, there is a perfect phase relationship between your breathing rhythms and your heart rhythms. That is, they are in perfect sync with one another.
Breathing and heart rhythms are the two most important mechanisms involved in the neuroregulation of the heart. As with your breathing, you can consciously alter your natural heart rhythm (known as the "baroreflex") to a certain extent. When they are in perfect sync, studies show that it helps strengthen and balance the autonomic nervous system. Once you learn to find your resonant frequency pattern, you will notice it induces feelings of mind-body relaxation.
One of the most useful features of the StressEraser is that it does not give credit if there is a disruption or "break" in the flow of a wave because of withdrawal of vagus nerve activity. These breaks might be caused by a variety of factors, including:
- Extending the exhale for too long
- Strained or improper breathing
- Excessive emotion
- Being highly distracted
- Fever or illness
- Specific medications blocking vagal regulation
- Or irregular heartbeats
The StressEraser recognizes these breaks and informs you that a disruption occurred. Let's take the example in Fig. 14. The area indicated by the circle in the middle is usually indicative of an exhale that is extended for too long. This causes the wave to rise and fall without obtaining sufficient variability. The smaller circle in the upper right represents a wave that appears to have sufficient length; but because it subtly rises and falls at the peak, the user was not given credit. This break is most likely due to distraction or emotion. Since the StressEraser's feedback is in real-time, you can immediately correct the behavior that caused the wave break. Typically, a wave break is your cue to re-focus on your breathing.
In summary, the StressEraser is a tangible biofeedback device that was specifically designed to help you find the unique breathing pattern that maximizes RSA, maintains your focus, and most efficiently triggers increased vagal influences on your heart. Therefore, the StressEraser promotes health and calmness. It can be used to reduce stress for those who have issues dealing with constant stress, brief stressors (i.e., deadlines, public speaking) or to simply enhance health, performance and overall feelings of calmness. Read the reviews, testimonials, and research and decide for yourself if the StressEraser is right for you.
Part 6: Glossary of Acronyms
ANS - Autonomic nervous system
BPM - (Heart) beats per minute
HRV - Heart rate variability
PNS - Parasympathetic nervous system (the relaxation branch of the ANS)
RSA - Respiratory sinus arrhythmia
SNS - Sympathetic nervous system (the "fight or flight" branch of the ANS)