Thank you for the inspiration and the starting point!
I’ve been updating the script(s) every day, I’ve been a bit obsessive, but I’ll have to take a break because of my vacation! 
I’m about to update the newer script, pretty minor changes – I decided that I needed a wider range between the quiet peaks at the beginning and the louds ones later on, so I changed percent_of_max from 50 to 25 (so now it goes up in increments of 5 from 25 to 100, instead of 50 to 100).
I also changed the volume check, so that it plays 100%, 50% & 25% (to reflect the above change), but I also made it so that e.g. 50% is actually 50% between min_vol and max_vol, instead of just 50% of max_vol.
Oh, and the dialog displayed during the initial delay now also shows the initial delay in hours – if you are really sleepy, it might be hard to remember that, yes, 240 minutes is 4 hours! 
There are several other similar little changes I’d like to make, and eventually (if I’m still interested, or someone else is) it would be nice to improve the way that you customize the settings – it is sort of annoying the way it is now, I usually prefer to just edit the applescript!
Anyway, off to bed… I can’t believe I’ve been reading about lucid dreaming, electrodermal response and sympathetic nerve activity all day long instead of, you know, eating, showering, doing some laundry, packing for my trip, and uh, figuring out how I’m getting to the airport tomorrow morning! 
Hopefully I’ll figure it out while I’m sleeping… 