Cardiac coherence is a breathing technique that helps manage stress and anxiety. It works by synchronizing the heart's rhythm with the breath, promoting a calmer state. Dr. Jean-Christophe Seznec, a psychiatrist, notes that it can be used alongside meditation and grounding techniques. The method relies on a natural physiological process called respiratory sinus arrhythmia, where the heart rate naturally speeds up during inhalation and slows during exhalation. By slowing and regularizing the breath, the technique enhances heart rate variability, a sign of a relaxed nervous system. Abdominal breathing, a key part of cardiac coherence, engages the abdomen rather than the chest, stimulating the vagus nerve. This nerve is part of the autonomic nervous system, specifically the parasympathetic branch that promotes rest and recovery. Studies from 2022 suggest that the body can respond to slow breathing within minutes. A 2026 study found that five minutes of slow breathing reduced stress in participants, though effects may vary among individuals, particularly those with high anxiety. The duration of cardiac coherence's effects can be hard to measure. Some research shows that stress markers can remain altered for up to 30 minutes after a session. However, the effectiveness depends on the individual, and the technique is mainly preventive, much like brushing teeth to prevent cavities. For lasting benefits, regular practice is more effective than isolated sessions. Studies on 484 participants showed reduced stress and anxiety with programs that included breathing and heart rate variability exercises. However, the exact time needed for results varies, and Dr. Seznec recommends daily practice over several days or weeks, often combined with mindfulness. For sleep, a session before bedtime can help relaxation, though effects are less immediate. A 2026 study on 457 people found that practicing slow breathing before sleep improved sleep quality over 28 to 30 days. While a month is often suggested, the key is regularity rather than a specific time frame. Regarding food cravings, the technique can create a pause between the desire to eat and the actual craving, with regular practice offering more lasting effects. Practicing cardiac coherence for a few minutes daily is generally achievable and recommended for long-term benefits. Research reports few adverse effects, but if dizziness or discomfort occurs, it's best to stop and return to normal breathing. While it can complement medical treatments, it should not replace them for severe anxiety. The 365 method, promoted by Dr. David O'Hare in France, suggests three sessions a day with six breaths per minute for five minutes, but it's a practical guideline rather than a strict rule. Studies vary in their methods, so three sessions a day are not proven essential for results. Cardiac coherence is simple and can be done almost anywhere, typically sitting in a quiet place with an upright posture. Tools like smartphone apps, guides, or sound-based techniques can help maintain the correct rhythm, though no equipment is necessary. Free online resources are available, and breathing should remain comfortable, avoiding hyperventilation or discomfort.