I was going to make a post about nicotine patches and vivid dreams because that's what I experienced. Anyways, before I posted, I thought I'd give it a search and see if its been discussed, which it has. I wonder if caffeine patches might yield a similar outcome w/out the risk of getting horribly addicted. Anyways, in the post I found someone was discussing ZME and nicotine patches, I still have no idea what ZME is but it lead to a search which lead to this article about specific frequencies and lucid dreaming.

I'm unable to post links so search for "lucid-dreaming-electrical-trigger-042342" (zme science)

I had read some time ago about the use of alternating current stimulation at certain frequencies producing a much higher number of reported lucid dreams in test participants than control. The article above suggests 40hz may be the key.

Then I searched simply 40hz and found another curious blog regarding someone subjecting his wife (who has Alzheimer's) to an hour of 40hz per day, and he reports her becoming mentally clearer. Then he lists some medical research studies, and well here's the link.

Again, can't post links yet but search for "Does listening to a 40 Hz tone" and look for the blog.

This would require testing of course but I don't have a quality subwoofer capable of producing low distortion 40hz sound.