PS - I followed the link and there’s a Pink Noise “sleep app”.
When you’re in deep sleep, the app starts playing pink noise until you hit a lighter stage of sleep.
Don’t recall if the research was from their app (think so!) or the 200-EEG-sensor setups.
Took me a couple back-tracks to realize this, and been meaning to share.
Only for iPhone.
(gonna see if I can link this over to the Tech topic thread)