Thank you for the video, but I have some feedback. The sound level equalization is __atrocious__. I tried on different headphones and headsets to confirm. I just don't think headphones with their tiny speakers can produce loud enough vibrations at frequencies as low as 60Hz. If you don't think this is a thing, you can look up resonance frequencies: each speaker has a certain frequency at which it sounds the loudest. This depends on the tension and size of the surface, just like guitar strings. Strings for lower pitches are made thicker, and when you need to go even lower, for example for a bass instrument, the strings are significantly longer.
Alright so point is, perhaps the lowest you'll want to go in each ear is 200Hz, random number, it'll take some testing. Also, I don't think anyone will manage to wear headphones for 8 hours: people turn and tumble during sleep. So you'll have to test for headset use. Here's a pair I have which are completely comfortable to wear during sleep: they're called AKG and they have very slanted in-ear protrusions.

If you do make a video with a higher base pitch, please tag me! I'll subscribe either way.
Sorry I missed this post originally! YouTube's robots definitely altered the audio track after I uploaded this monstrosity of a video. You might like the sound of my customizable sleep tracks better, which were only 90 minutes each and not altered from what I can tell. I also raised the base frequency a bit, and tested my smaller-size/lower-priced headphones to make sure they could all play the tones clearly. If you haven't already discovered them, you can get started here: https://www.youtube.com/watch?v=VZMwNi8IPXs
Alex Han