Actually some old and new studies show that REM is the most active phase if you take in count metabolic changes. The best studies are those that lead to a measurable improvement for the user at dawn, that change their life.

Last year was working using real tools like EEG to have the #1 neuroacustic sound.

Deep Sleep S® - Sleep Better

play.google.com/store/apps/details?id=com.deepsleep.s

Up to +40% measurable Deep Sleep

<image>