Oh, my! Jody H, you are so wonderful to post such a great video with the fantastic graph to show what's going on during the 90 min sleep!!!  I have researched online, yet I couldn't find find anything like what you did here, to answer my queries about WHAT hz occur during DEEP SLEEP.  Thank you for showing the graph.  
Have you read the article about the medical publication about the experience for 3hz with binaural of 220 and 223 being effective frequency for deep sleep?  I have tried various delta waves, yet for me the lower the delta wave the better for my personal experience, which is kind of similar to what you did on this video.
*My question for you here is what the two solfeggi frequencies did you use to make the hz difference between left and right ears???  I read online about 432 Schumann as well as 528 being the most effective frequency to deep sleep.  HOWEVER, they seem to be too high for my taste.  Can you also explain/clarify the binaural pure hz let's say delta wave of 1.5hz along with background music? I'm NOT getting the idea or concept of the combiation.  Why would the background not interferring with the pure 1.5hz into our brains???
I also like what you said under the show note about your personal opinion about listening to first 90 min max and let your brain to relax.  I totally agree concept wise, yet I'm just a weirdo.  I cannot seem to be able to relax after that.  I have insomia problem, yet I could fall asleep after 10-15 minutes of having my headphones on listening to binaural pure beats @1hz.  Once I feel I fall asleep, I have to take my headphones off.  For I'm a side sleep, I have to catch the moment while I am falling a sleep while still facing the ceiling.  Once I pass that point, my sleep would be terrible.  
As I said, I can fall sleep with 1hz successfully, yet once I take my headphones off not listening to the waves, my brain cannot continuously sustain the same way.  Thus, I'm thinking of actually using isochronic or monaural beats and playing them with speakers for 8 hours.  I did try isochronic before, but only once.  Because the gap between the waves bothered me.  They sound like fire cracker on New Year's Eve to me.  Any non sustained sound wakes me up.
Have you thought of making MONAURAL BEATS?  
Thank you for your reading my long post
Hey, I'm really sorry, I just had a baby a couple months ago and have very little time to reply to comments ... would you be able to post again, but a bit shorter?
Judy Huang