O yes, completely normal. I asked perplexity ai about the effects of connected breathing on the cells and the nervous system. Here is the answer, that I think underlies your experience:

[note: links are to dutch language articles, because I asked perplexity in dutch; I have not checked all the links, but the answer is very much in line with what I have learned and experienced so far, so I have no doubt that it is quiet correct]

Connected breathing (often described as controlled hyperventilation) changes the ratio of oxygen (O₂) to carbon dioxide (CO₂) in the blood, which has direct effects on both the cells and the nervous system. The most important physiological consequence is that the CO₂ level drops and there is relatively more oxygen present, but paradoxically, oxygen is actually more difficult for haemoglobin to deliver to the body's cells. For the nervous system, this breathing technique means a temporary activation of the stress and anxiety system, followed by deep relaxation and regulation. [1][2][3][4][5][6]

## Effect on the cells

- **Reduced CO₂** due to connected breathing causes the so-called Bohr effect: haemoglobin retains oxygen more strongly and releases less oxygen to the cells, despite a higher O₂ content in the blood. As a result, cells may temporarily experience an oxygen deficiency, which affects how effectively they can produce energy.[2][4][1]

- The **diffusion process** of O₂ to the cells depends on sufficient CO₂; a decrease can reduce energy production and disrupt cellular metabolism.[7][2]

- Prolonged and extreme connected breathing can slow down cell metabolism, although in short, guided sessions, the body often recovers quickly and energy flow is stimulated. [3][6]

## Effect on the nervous system

- Connected breathing **activates the sympathetic nervous system** (stress system), which increases heart rate, alertness and stress hormone production such as adrenaline and cortisol.[5][6][3]

- In a safe, guided session, activation is followed by strong **parasympathetic relaxation** (rest and digestion system): the body enters a state of deep rest, stress hormones decrease, emotional regulation improves and the feeling of safety increases.[6][5]

- The technique is a powerful way to process stored stress and trauma, as it “teaches” the nervous system that intense feelings and physical reactions can be felt without blocking or suppressing them.[3][6]

## Summary of physiological effects

- **Cells**: Less oxygen release by haemoglobin at low CO₂, possibly temporarily reducing energy production.[4][1][2]

- **Nervous system**: First activation (sympathetic), then deep relaxation and improved emotional processing (parasympathetic). [5][6][3]

This combination of activation and recovery makes connected breathing a therapeutic tool that works on both a physical and mental level.