How does HEG increase the bloodflow to the PFC?

I get the infrared sensor that's measuring oxygen levels/blood in my PFC, but what I'm confused about is how is this increased over time, especially by me just sitting and staring at the screen?

I'm curious how this works and do think the science is accurate, but I'm also partly confused and thinking I'm doing it wrong/I should be trying to focus in a particular way.

Can someone help me understand exactly how using this device improve blood levels in the PFC, and also apparently mood, focus, etc.?

Thanks