A precursor to modern sound and light devices such as the Brain Machine, Brion Gysin and Ian Sommerville’s Dreamachine -

In its original form, a dreamachine is made from a cylinder with slits cut in the sides. The cylinder is placed on a record turntable and rotated at 78 or 45 revolutions per minute. A light bulb is suspended in the center of the cylinder and the rotation speed allows the light to come out from the holes at a constant frequency, situated between 8 and 13 pulses per second. This frequency range corresponds to alpha waves, electrical oscillations normally present in the human brain while relaxing.

A dreamachine is “viewed” with the eyes closed: the pulsating light stimulates the optical nerve and alters the brain’s electrical oscillations. The “viewer” experiences increasingly bright, complex patterns of color behind their closed eyelids.

- Dreamachine on Wikipedia

More info and build documentation regarding the Dreamachine is available from Kaden Harris’ Eccentric Cubicle – The Gysin Device
In the Maker Shed:

Eccentric Cubicle