In nondirective meditation, deep relaxation comes as an automatic response to the inner practice.
Tense muscles loosen up, heartbeat and breathing slow down, mental stress is released, thoughts and memories pass freely through the mind. Physiological measurements have identified changes in the autonomic nervous system that affect heart rate, breathing, and blood pressure. Functional MR scanning of the brain has shown that nondirective meditation activates a neural network for spontaneous mental processing. This chapter discusses some of the studies that have provided important clues as to how nondirective meditation reduces stress and enhances emotional processing.
One of the intriguing features of nondirective meditation is that stress reduction comes more or less automatically. Its relaxing effects during practice come in response to the effortless repetition of a meditation sound, allowing thoughts and other experiences to emerge and pass freely. This is in contrast to directive practices, in which stress reduction comes by intention— for example by tensing and relaxing specific muscles, controlling the pattern of breathing, or actively focusing awareness on what goes on in mind and body from moment to moment.
Another astounding feature of nondirective meditation is that the relaxing effects seem to be greater than when we try to produce them directly. At first glance this may come as a surprise, as many experiences in life have taught us that we have to work hard to achieve the best results. But in reality, this is not always the case. In meditation, the cliché “less is more” is actually true: the less effort, the more relaxation. Maybe it is not so surprising after all?
Nondirective meditation mitigates stress reactions of which we are normally unaware and that are usually beyond our control. Most of us are unable to sense when our blood pressure is elevated, unless it is so high that it causes severe headache or pounding in our chest. Even when we are told it is high, few of us can reduce it just by applying our will. The same goes for muscular tension in our neck and temples. We are unaware that it causes stiffness and tiredness until the stress level is quite high. Although we know that tension causes headache, we are unable to stop the pain by directing the muscles to relax. In fact, regulation of blood pressure, heart rate, and most other functions involved in stress and relaxation work independently of our conscious will. Hence, these functions are called autonomic, which literally means self-regulated.
Much to our surprise, we sometimes experience bodily signs of arousal, fear, or shame without knowing why. Our hands may be trembling and palms sweating, the face may be blushing, the heart may be pounding, and we may have a strange gut feeling, without intellectually recognizing any reasonable emotional cause. The reactions come automatically and cannot be controlled directly by intent.
The most important regulator of stress and relaxation is a brain network called the limbic system. This neural network operates more or less independently of our conscious mind and reacts to physiological and sensory signals of which we are usually unaware. Based on a number of external and internal stimuli, it continuously monitors challenges to our physical and psychological well-being, and sets the level of readiness accordingly. If a potential threat is detected, the increased level of readiness is automatically secured by signals to the brain, heart, muscles, and other organs involved in stress responses. When the incident is over, the alert is cleared. Body and mind can relax, and equilibrium is restored.
Considering that so many of our stress reactions are beyond the limits of our conscious control, it is quite amazing that nondirective meditation can reduce physical and mental stress reactions—not by a conscious, intentional act of will, but indirectly, by performing the technique in an effortless manner. A closer look at the mechanisms explains how.
Practicing nondirective meditation induces changes in the autonomic nervous system that are the opposite of those associated with stress. During meditation, breathing and heart rate slow down, muscle tension is released, and metabolism is lowered. Blood pressure does not always change during a single sitting, but often goes down with regular practice. These changes were first described with Transcendental Meditation in the early 1970s by the American cardiologist Herbert Benson and colleagues at Harvard University (Wallace et al., 1971).
In his book The Relaxation Response, Benson (1975; 2000) suggested that the physiological changes during meditation occur as a response to the stimulation of distinct areas in the limbic system. Similar phenomena had first been described by the Swiss Nobel laureate Walter Hess (1957), and according to Benson this adaptive biological mechanism helps the body to rest and protects it from harmful levels of stress. The researchers were amazed to find that physiological relaxation occurred more rapidly and reached a deeper level than during sleep and hypnosis, and suggested that it might have practical applications (Wallace, 1970; Wallace et al., 1971). Benson’s book described a secular version of nondirective meditation that he called the Relaxation Response. Somewhat confusingly, this term is used both to refer to this type of nondirective meditation and to its physiological effects. (In this book, we distinguish the meditation technique from the physiological mechanism by capitalizing the former but not the latter.) During the following years, a large number of scientific studies have identified the physiological effects and mechanisms of nondirective meditation (Buttle, 2015). Some of these discoveries are discussed below.
Many cultures have proverbs saying something to the effect of “the eyes are mirrors of the soul.” When it comes to emotions, stress, and relaxation, however, the heartbeat is probably more informative. In love, for example, usually “the heart knows before the mind.” When we meet the right person, many of us have experienced that our body reacts long before the brain understands what is going on.
Almost any kind of emotion, positive or negative, is accompanied by a change in heart rate. This may be utilized to detect emotional reactions that the mind does not know, is not aware of, or does not want to admit. Therefore, heart rate is one of the key components of an instrument called a polygraph or lie detector. Any change in pulse may disclose an emotional reaction to the object or scenario presented to the person being tested. Hence a big problem arises when it comes to interpretation. How can we be certain of what a polygraph reaction actually means, when a change in heart rate may reveal joy or fond attraction as well as an angry or fearful response? Unfortunately the lie detector does not always tell the truth. Nevertheless, variations in heart rate are a useful tool for studying the details of autonomic nerve activity during stress and relaxation.
When we are stressed, the heart rate goes up, and when we relax, it returns to a normal resting level. As shown in Figure 4.1, heart rate gives a good indication of stress reduction during nondirective meditation. A rapid reduction of the physiological stress, beyond a normal resting level, occurs within the first 5–10 minutes. Thereafter, a modest continuing decline gradually develops for the next two hours. These findings demonstrate that nondirective meditation gives efficient and effective relaxation, beyond the levels of ordinary rest.
Figure 4.1. Physiological relaxation during nondirective meditation. The green line demonstrates a rapid reduction in heart rate during the first 5–10 minutes of nondirective meditation (Acem Meditation). Then a modest continuing decline gradually develops during the next two hours. The broken turquoise line shows that there was no change in a control group resting as fully as possible without performing any specific technique. Adapted from Solberg et al. (2004).
These results were obtained in a study by the Norwegian cardiologist Erik Ekker Solberg and colleagues at the University of Oslo in Norway (Solberg et al., 2004). The study included 38 people who had practiced the nondirective technique Acem Meditation for several years, and a control group of 21 healthy volunteers recruited through an occupational health service. The findings demonstrate that nondirective meditation induces a rapid reduction of physiological stress level within the first 5–10 minutes, indicating that nondirective meditation gives effective relaxation beyond the level of ordinary rest.
Relaxation can also be assessed by measuring reduced stress hormones in the blood. Some of the most important stress signals are transmitted by adrenaline (also known as epinephrine) and its sister hormone noradrenaline (or norepinephrine). During physical activity and mental stress, electrical impulses from the brain travel via sympathetic (stress-inducing) nerves to the heart, arteries, and other target organs all over the body. When the electrical signals reach the organ, small packets of noradrenaline are released from the nerve endings. Most of the hormone binds to receptors on the cells, where it triggers the stress responses, and some of it spills over to the blood. This typically increases heart rate and blood pressure within a few seconds. Sympathetic nerve activity also stimulates the adrenal glands to release adrenaline, which is circulated in the blood stream, thereby amplifying stress reactions in organs all over the body, including the brain. The release of adrenaline and noradrenaline is usually brief, and typically changes within seconds to a few minutes. Resting concentrations of these hormones in blood is therefore an excellent indicator of the stress reactivity of the individual.
In a study from Cordoba in Spain, Infante and colleagues reported that people who practiced the nondirective technique Transcendental Meditation on a regular basis had 30–40 percent lower levels of adrenaline and noradrenaline at rest conditions outside their regular practice (Infante et al., 2001). They also found that there was less variation in their levels of these hormones, compared to control participants who did not practice meditation. Together, these findings indicate that regular meditators have a lower level of arousal and better stress tolerance in everyday life.
Direct evidence that meditation lowers sympathetic nerve activity was first demonstrated in a study of African-American men with hypertension and kidney disease (Park et al., 2014). To determine the role of sympathetic nerve activity, Dr. Jeanie Park and colleagues at Emory University, Atlanta, measured electrical nerve impulses by inserting tiny microelectrodes into one of the nerves in the leg. While the participants listened to a recording of meditative breathing and body scan instruction, sympathetic nerve activity declined in parallel with heart rate and blood pressure. In contrast, there was no change during a control experiment, in which they listened to a recording with educational information on how to detect and treat hypertension.
The reduction of sympathetic nerve activity, heart rate, and blood pressure during meditation was also associated with a reduction in respiration rate that did not occur in the control group. Therefore, a third series of experiments was performed, in which the participants followed instructions to voluntarily slow their breathing. Although they reduced their respiration rate to the same extent, this intervention did not change their sympathetic nerve activity, heart rate, or blood pressure.
Altogether, these findings indicate that the beneficial cardiovascular changes during meditation are associated with reduced sympathetic nerve activity, and that they are not merely a response to slower breathing.
The relaxing effects of meditation also involve parasympathetic nerves. Whereas the sympathetic system induces the challenging and protective “fight or flight” reactions, parasympathetic nerves support the more pleasurable “rest and digest” or “feed and breed” activities. This part of the autonomic nerve system contributes significantly to the relaxation response. By slowing the heart rate and reducing its pump activity, parasympathetic nerve activity lowers blood pressure. This effect is an important part of blood pressure regulation, and acts as a safety valve, preventing an overload in the cardiovascular system. Parasympathetic nerves are also paramount for some of our most satisfying physiological activities. Without their help, blood would not flow to sexual organs and intestines to sustain their functions in moments of need and desire.
The parasympathetic nerve activity during meditation has been less recognized by science than has the reduction of sympathetic activity, probably because it is harder to measure directly. The relevant nerve fibers are not readily accessible from the body surface. It is also not feasible to measure its transmitter acetylcholine, because it is immediately degraded locally and therefore does not spill over into the blood to the same extent as adrenaline and noradrenaline. Nevertheless, parasympathetic nerve activity is an active component of the relaxation response that can be measured indirectly by its more subtle effects on heart rate.
In addition to the increase and decrease in heart rate, subtle variations in the length of time between heartbeats reveal changes in the balance between sympathetic and parasympathetic activity in the autonomic nervous system. In a resting state, these variations coincide with our breathing pattern. When we inhale, the pulse slows down slightly, and when we exhale, it increases again. This cycle of pulse variation is called heart rate variability. Babies and toddlers have a very notable variation in heart rate. In general, high heart rate variability is a sign of a healthy cardiovascular system. Its parasympathetic component indicates a low risk for cardiovascular disease and sudden death.
An advantage of analyzing heart rate variability over simply counting the pulse is that heart rate variability can detect changes in parasympathetic nerve activity during nondirective meditation. This was demonstrated in a study carried out by the Norwegian cardiologist Anders Nesvold and colleagues (2012) at the University of Oslo (Figure 4.2).
Figure 4.2. Parasympathetic nerve activity during nondirective meditation. The “mountain ridge” maps heart rate variability that represents relaxing parasympathetic nerve activity. During nondirective meditation, the ridge is higher, indicating increased parasympathetic nerve activity. Adapted from Nesvold et al. (2012). As shown in Figure 4.2, the recordings from 27 healthy women and men demonstrated characteristic changes in heart rate variability during the nondirective technique Acem Meditation. Parasympathetic nerve activity gradually appeared after the eyes had been closed during seated rest, and a marked increase ensued when the meditators started to practice the technique. These observations indicate that nondirective meditation increases parasympathetic nerve activity during meditation and suggest that regular practice may favorably affect autonomic nerve regulation of the heart.
Nondirective meditation and some types of breathing meditation are typically associated with relaxed states of the brain and the body. However, practices that aim to induce positive emotions or to observe the thought process seem to be less relaxing. This was demonstrated in the ReSource project from Berlin and Leipzig, which compared the effect of training beginners in three traditional mindfulness practices (Lumma et al., 2015).
A group of 156 healthy women and men participated in a sequence of three 13-week extensive training modules:
(1) Breathing meditation similar to nondirective meditation aimed at increasing awareness of body sensations, (2) Loving-kindness meditation aimed to increase positive emotions and compassion, (3) Observing-thoughts meditation aimed to develop metaawareness of mental activities and detach from thoughts.
The extent of physiological relaxation and the participants’ subjective experiences of the practice were assessed after three and thirteen weeks of training of either technique. Relaxation was measured as lower heart rate and higher heart rate variability during meditation.
As expected by the researchers, loving-kindness and observing-thoughts training were rated as more effortful than breathing meditation, probably because they involved mental tasks that required more attention. Consequently, heart rates were higher and heart rate variability lower, indicating higher levels of arousal and lower levels of (relaxing) parasympathetic nerve activity.
Contrary to the working hypothesis of the researchers, the difference between the more relaxing breathing meditation and the two other methods increased as the meditators became more familiar with their techniques. With loving-kindness and observing-thought meditation, heart rates were higher and heart rate variability lower at week thirteen. This indicates an even higher degree of effort than at the beginning of training, whereas breathing meditation maintained its relaxing effect unchanged.
These observations indicate that techniques aiming at inducing positive emotions or at creating a meta-awareness of thoughts involve more mental effort and less physiological relaxation than do effortless breathing meditation. The differences seemed to increase rather than abate over the first three months of practice.
The studies we reviewed in the first part of this chapter showed that the relaxing effects of nondirective meditation are associated with typical changes in the autonomic nervous system. They also suggested that techniques performed without effort induce stronger effects than when attention is focused in a specific direction. These findings concur with some intriguing observations of what goes on in the brain during nondirective meditation. Contrary to what we might expect, certain types of spontaneous mental activity increase when the brain is not pursuing any specific task. The rest of this chapter presents some ideas on how the relaxation response in nondirective meditation is linked to mental processing and stress reduction.
For many years, electrical wave measurement was the main source of information of what goes on in the brain during nondirective meditation. As shown in Figure 4.3, general patterns of brain activity can be measured by attaching electrodes to the scalp using a method called electro-encephalography or EEG. Although the brain waves cannot reveal what we think and feel, the frequency of the waves gives information about the type of activity going on in the brain from moment to moment.
Brain-wave bands in the figure: beta waves (14-30 Hz) are associated with a normal waking state; alpha waves (8-13 Hz) with deep relaxation and light meditation; theta waves (4-7 Hz) with deep meditation, memory, imagery, and light sleep; and delta waves (< 3.5 Hz) with deep rest or sleep.
Figure 4.3. Electrical brain waves and mental activity. Electrical brain waves are measured by gently attaching electrodes to the skin of the scalp with a special cap. Type of electrical activity is named according to frequency given in Hertz (1 Hz = 1 cycle per second). Typical mental activities are listed for each wave type. Fast beta waves are typical for waking goal-oriented brain activity, whereas slower alpha and theta waves are associated with deep relaxation and meditation. (Adapted from Abhang et al. (2015).)
Figure 4.4. Brain waves during nondirective meditation. Alpha and theta are the most abundant brain waves at rest. Both wave types increased most prominently during the practice of Acem Meditation, demonstrating deep wakeful relaxation in nondirective meditation. There was also some delta activity, but not much more than during ordinary rest. The low levels of beta activity indicate that there is no concentration on goal-oriented tasks and little or no attention is paid to sensory activity. (Adapted from Lagopoulos et al. (2009).)
The results shown in Figure 4.4 were obtained in experienced practitioners of Acem Meditation in a study performed by the Australian neuroscientist Jim Lagopoulos and co-workers (2009). The bars demonstrate that alpha waves were the most abundant type of brain wave during nondirective meditation. These waves are characteristic of a wakeful, relaxed state of mind that typically occurs when the meditator closes his eyes and rests without engaging in any specific task. Their dominating presence indicates that nondirective meditation is a wakeful, resting state of mind. Moreover, the clear increase in alpha waves from ordinary rest to nondirective meditation indicates the deep relaxation associated with this form of meditative practice.
Slower theta waves also increased and were the second-most abundant. This wave type indicates deep relaxation of the brain and occurs during meditations of experienced practitioners, or else only in the first phase of sleep. As in the case of alpha waves, the increase in theta waves from ordinary rest to nondirective meditation also reflects deep relaxation. There were not many of the slower delta waves typical of deeper levels of sleep. Also, there were only minimal amounts of the faster beta waves, which are characteristic of problem solving and other goal-oriented activities. For technical reasons, fast gamma waves were not recorded. In summary, the measurements show that brain activity during nondirective meditation is different from concentration and sleep, although it involves deep relaxation of the body.
As we learned from the comparison of different types of mindfulness meditation in the ReSource study from Berlin and Leipzig (see above), the techniques practiced without effort seem to yield more relaxation than those involving attention to achieve specific goals. This observation fits well with a study from Japan demonstrating that changes in autonomic nerve activity are associated with characteristic changes in brain activity.
In a study of 20 healthy students, Dr. Takahashi and colleagues from the University of Fukui measured brain waves and heart rate variability during a relaxed type of Zen breathing meditation (sosoku). While the so-soku technique is often performed with a narrow focus on counting the breaths, the participants in this experiment were instructed to allow spontaneous thoughts and other experiences to emerge and pass freely (Takahashi et al., 2005). The study demonstrated that this breathing meditation increased the abundance of alpha and theta waves, just like in nondirective meditation. It also showed that the amount of these waves correlated with the typical pattern of autonomic nerve activity. Meditators with large amounts of alpha and theta waves had high levels of parasympathetic (relaxing) nerve activity and low activity in sympathetic (stress-inducing) nerves. As we shall see in the following paragraphs, these observations point to an interesting link between the type of brain activity during nondirective meditation and stress reduction.
Alpha waves have been a hallmark of relaxed mental activity as long as brain waves have been measured. They emerge when the brain takes a rest and fade as it returns to goal-oriented tasks. Since they are the most abundant activity in the resting brain and easy to detect, alpha waves have been used in relaxation training (biofeedback). For many years, their origin and function during meditation were unclear. However, some clues came when their source was mapped to areas near the midline of the brain during nondirective meditation. Two studies on Transcendental Meditation indicated that the characteristic brain waves of meditation came from a network of brain areas that was called the default mode network or the resting state network (Yamamoto et al., 2006; Travis et al., 2010). As briefly described below, this network got its name precisely because it is active when the brain is not occupied with any specific goal-oriented task.
More specific information on how the brain works during rest and meditation has come from functional imaging of the brain by MR scanning (fMRI). Several studies have shown that the deep relaxation that occurs during nondirective meditation is associated with increased activity in the default mode network of the brain (Lazar et al., 2000; Engström et al., 2010; Travis et al., 2010; Xu et al., 2014). As described in more detail in chapters 3 and 4, this is a network of brain areas that underpin the spontaneous stream of inner experiences that we call mind wandering. Although this activity is sometimes nicknamed daydreaming, it comprises several useful types of mental activity. Besides daydreams and fantasies, a more precise definition also includes autobiographical memory, self-reflective thought, envisioning the future and considering the perspective of other beings (Buckner et al., 2008).
Whenever we take a rest from outward directed tasks that involve concentrated attention and some degree of mental effort, the amount of mind wandering and the activity of the default mode network increase (Mason et al., 2007). Similar changes typically occur in several types of nondirective meditation, including the Relaxation Response, Transcendental Meditation, and Acem Meditation (Lazar et al., 2000; Engström et al., 2010; Travis et al., 2010; Xu et al., 2014).
In contrast, meditation practice that involves concentration reduces activation of the default mode network. A study of the nondirective technique Acem Meditation showed that changing the way of performing the technique from nondirective, effortless attention to concentrated, effortful repetition of the meditation sound reduced the extent of default mode network activation, particularly in areas involved in episodic memories and emotional processing.
In a review of 17 studies reporting changes in default mode network activity (Simon & Engström, 2015), the majority of mindfulness techniques, including breathing meditation, loving-kindness, and observing-thoughts, were associated with reduced default mode network activity. This indicates greater cognitive effort, perhaps related to more emphasis on maintaining acuity in attention and wakefulness. However, there were also a number of mindfulness studies that clearly demonstrated increased default mode network activity. Although several factors may have influenced the outcome, it is conceivable that the differences result from more versus less effortless practicing.
The mental activity associated with the default mode network is a form of spontaneous self-debriefing. It occurs when the brain is not busy doing other things—when we rest or engage in activities that do not demand too much attention, such as nondirective meditation. An important function of the activity of the default mode network is to revisit disturbing, challenging, or unfinished experiences in order to put them to rest. Whenever we have a good break from challenges in our environment and attention-demanding, goaloriented activities, the default mode network engages in spontaneous mental processing. By replaying stressful and challenging episodes and comparing present and previous experiences, the brain tries to make sense of new experiences by putting pieces of the puzzle together. According to experts in the field, the default mode network activity represents a special type of mental processing that helps us better understand our position in life by spontaneous reflection on three related areas of interest:
1) Consolidating the understanding of challenging situations in our personal history, 2) Exploring our own ideas of how we are perceived by other people and how we should best relate to them, 3) Forming scenarios of what might happen to us and contemplating plans for the future (Mason et al., 2007; Buckner et al., 2008).
From this perspective, mental processing during nondirective meditation and other resting states may serve adaptive functions beyond random divagations of the mind. By processing information from the autobiographical memory and emotional reactions, the default mode network expands our perspective beyond the present moment. This often leads to a better understanding of the challenges in our current situation and supports problem solving and preparing for the future. In this way, it reduces the perceived uncertainty for and potential threat of the well-being of the individual, thereby alleviating the physiological and psychological level of stress. In fact, it has been suggested that normal functioning of the default mode network may be an important marker of positive mental health effects (Simon & Engström, 2015).
The changes in the brain, heart, and mind presented in this chapter suggest that there are important links between the relaxed, effortless practice of nondirective meditation and the mechanisms leading to its results. Some of the studies indicate that spontaneous mental processing within the default mode network is increased during nondirective meditation. This may be an adaptive mechanism for processing challenging experiences. Over time, this mechanism reduces bodily and mental stress and mitigates psychological symptoms. Other studies show how nondirective meditation modifies stress signals from the brain to the heart, blood vessels, and other organs, by changing the activity of autonomic nerves and stress hormones.
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