Glossary

Acceptance and Commitment Therapy. A third-wave therapy developed by Steven Hayes. Rather than trying to change or reduce difficult thoughts, ACT teaches you to observe them without identifying with them, to accept them, and to act in accordance with your values despite their presence. The paradox of control is central: trying to control your thoughts and emotions generally makes the problem worse.

An almond-shaped structure in the limbic system, the center for processing fear and threats. It activates in the face of real threats but also imagined ones — including ruminations about the future. Regular meditation reduces the thickness of the amygdala and its resting activity level, which partly explains the reduction in anxiety observed in meditators.

A physiological state where heart-rate variability (HRV) enters resonance with the breathing rhythm. Reached at around 6 breaths per minute (5s in / 5s out). At this rhythm, the cardiac baroreflex oscillates in sync with the breath. Measured effects include reduced cortisol, improved HRV and emotional regulation.

A brain network active when the brain is not focused on an external task — during daydreaming, rumination, planning the future or thinking about oneself. Studies show that a wandering mind is a less happy mind (Harvard, 2010). Meditation reduces default-mode activity and strengthens the connection between this network and the attention regions.

A state of total immersion in an activity, described by psychologist Mihaly Csikszentmihalyi. Characterized by intense concentration, a loss of awareness of time, and a merging of action and consciousness. Different from mindfulness — flow is oriented toward an external task, mindfulness toward inner experience — but both share the absence of rumination and mind-wandering.

A fundamental concept of Buddhist philosophies: everything that exists is in constant transformation. Nothing is permanent, neither pleasures nor sufferings. Recognizing impermanence is not nihilistic — on the contrary, it allows you to be fully present to what is, knowing it will change. It is also an antidote to excessive attachment and resistance.

Mindfulness-Based Cognitive Therapy. A cognitive therapy based on mindfulness, developed by Mark Williams, John Teasdale and Zindel Segal. A combination of CBT and MBSR, specifically designed to prevent depressive relapse. Studies show a 43% reduction in relapse risk among patients who have had three or more episodes.

Mindfulness-Based Stress Reduction. An 8-week program created by Jon Kabat-Zinn at the University of Massachusetts in 1979. It combines mindfulness meditation, gentle yoga and exploration of stress reactions. It is the most scientifically studied program — more than 700 published studies confirm its effects on anxiety, chronic pain and depression.

A state in which attention leaves the present task for unrelated thoughts: daydreams, ruminations, anticipations. Harvard research (Killingsworth & Gilbert, 2010) shows that the human mind wanders 47% of the time on average, and that this state is associated with lower subjective happiness, regardless of the task being performed.

A state of intentional attention to the present moment, without judgment. Jon Kabat-Zinn defines it as 'paying attention in a particular way: on purpose, in the present moment, and non-judgmentally.' It is not a state of relaxation or mental emptiness — it is a quality of attention.

The brain's ability to change structurally and functionally throughout life in response to experience. Regular meditation produces measurable changes in brain imaging: increased grey-matter density in the hippocampus and the anterior cingulate cortex, reduced amygdala activity. These changes have been measured after just 8 weeks of regular practice.

The branch of the autonomic nervous system responsible for rest and recovery ('rest and digest'). It opposes the sympathetic system ('fight or flight'). Activated by slow, deep breathing, cardiac coherence and meditation. Its activation lowers heart rate, reduces blood pressure, and promotes digestion and recovery. It is the central mechanism by which conscious breathing regulates stress.

The frontal area of the brain associated with emotional regulation, decision-making, sustained attention and self-awareness. It is the region that mindfulness trains directly. It exerts an inhibitory role over the amygdala — the more active and thicker the prefrontal cortex, the less the amygdala overreacts to stress.

An acronym developed by Tara Brach for working with difficult emotions. Recognize (identify what's happening), Allow (let the experience be there), Investigate (explore with curiosity what's happening in the body and mind), Nurture (offer yourself compassion). This sequence transforms your relationship to emotional discomfort without trying to suppress it.

One of the oldest Buddhist meditation techniques, meaning 'to see things as they really are.' It consists of systematically observing bodily sensations, thoughts and emotions with equanimity. Vipassana retreats typically last 10 days in complete silence. Jon Kabat-Zinn drew heavily on Vipassana to develop MBSR.