I remember a 'body-hack' fad around inducing lucid dreaming via sleep masks. IIRC, it used EMG sensors to detect eye muscle movement and then it would flash an LED mounted inside the mask in an attempt to slightly wake you up during REM. Can anyone speak to the method's efficacy?
I built this a few years ago: https://fellerts.no/projects/eog.php. It only gave me intense nightmares. It was a cool project though, and I'm sure it could work for some people.
Interesting aside speaking of lucid dreaming- at least one of the authors of this paper is a lucid dream researcher - Karen Konkoly at Northwestern. Another people she coauthored studies conversing with lucid dreamers while they're mid-dreaming. Interesting stuff.
