A recent study has demonstrated that a coupling between breathing and neural activity may extend throughout the brain. Effectively, how quick and heavy you breathe can directly affect your brainwaves. This explains part of the effects from meditation.
The study found that slow bands of brain activity (theta, delta) were significantly enhanced through slow mechanical respiration. This effect was seen across the entire cortex. There was also a shift and reversal of the flow of information in the brain from wake-like to sleep-like. Together this resulted in the perception of an altered state of consciousness.
It is unclear how exactly theta and delta activity relate to visual snow, but disruptions in these bands are linked with various pathologies and certainly sleep issues. Indirectly issues with sleep may also contribute to heightened cortical excitation.
There was no significant finding for the gamma rhythm linked directly in visual snow (although other studies have found that meditation can modify gamma waves too). On a long-term basis there may be other effects from practicing controlled breathing.
Breathing: What Else To Consider
Slow-paced breathing is also coupled to attention, it has benefits for promoting “mindfulness”.
The way you breathe may impact on visual snow in other ways relating to what constitutes the air you breathe, namely oxygen and carbon dioxide and for example with controlling oxidative stress. From this perspective what may be best is also slow, minimal, diaphragmatic breathing, almost always through the nose – even during most exercise (for more info on this read about “the Buteyko method”).