Now that we know that breathing practice or breathing-based meditation can activate the vagus and improve mental and physical functioning, which of the varying breathing techniques should we do?
The study by Yilmaz Balban et al. (2023), "Brief structured respiration practices enhance mood and reduces physiological arousal," addresses this issue by comparing mindfulness-based meditation with three patterns of structured breathing. Mindfulness meditation involves a passive observation of breathing sensations, whereas structured breathing imposes control of each breath.
The researchers were particularly interested in anxiety and the difference related to inhaling and exhaling. Inhaling increases heart rate (associated with sympathetic activation), whereas exhaling slows heart rate down (associated with parasympathetic activation).
Key points include:
- The three types of controlled breathing were box breathing, cyclic sighing, and cyclic hyperventilation with retention.
- Box breathing is also called "tactical breathing" and is used by the US military for improved stress resilience and performance. It involves equal inhale, hold, exhale, hold durations. So for instance: inhale for 2 counts (or whatever), hold for 2 counts, exhale for 2 counts, hold for 2 counts.
- Cyclic sighing involves deep breaths followed by longer exhales. It has been linked to "psychological relief" and changes in autonomic function. The emphasis is on the exhale.
- Hyperventilation with retention emphasized longer duration of inhaling, that more intense than exhales. This is a paradoxical breathing technique, in that it can occur naturally during anxiety and panic, but when done deliberately it can be therapeutic.
- The participants were divided into 4 groups according to breathing technique, and tested on state and trait anxiety, mood (positive vs. negative affect), as well as heart rate, heart rate variability (a measure of vagal tone), respiration, and sleep. They were tested again after 28 days, the end of the study.
- All of the techniques improved mood and anxiety scores, but the active controlled breathing groups had bigger effects than the passive mindful observation of breath.
- There were no effects on sleep (self-reported) in any group.
- The controlled breathing groups had greater changes in respiratory rate (high rate correlates with anxiety) such that their resting respiration was slower. This slower respiratory rate was correlated with greater daily positive affect.
- The researchers also found that the beneficial effects were cumulative, such that daily effects were greater the more days that the participants practiced.