Finally got my headlight working. Man, what a difference that makes. I noticed that it seems to turn off on the descent when riding counter-clockwise. Particularly the “S” turn before you hit the sprint point. The road illuminates once again just as you approach the sprint banner.
Just an FYI for those who want to know how to turn on the headlight - it’s a function of your graphics card. If you don’t see a headlight your graphics card is not sufficient to support that level.
@Greg: Kind of. The Zwift program will make some determination based on your hardware, but as many in the thread below discovered, that determination is conservative. Information about how to enable can be found here:
https://support.zwift.com/hc/communities/public/questions/201559235-Graphics-Quality-?locale=en-us
But users should understand that manually editing the config files is unsupported and at your own risk…although I suppose worst case scenario you just download and reinstall.
Well, worse case is more like you cook your computer and have to send it to the shop for repairs. 
Definitely cranking up your settings to max on an older computer is risky and unsupported for a reason. From what I’ve seen the reduced frame rate/lack of being able to notice improvement has been keeping most of the modders using modest settings enhancements.
For me I just left it at the headlight alone.
…and I was just trying to head off the stream of questions asking how to turn the headlight on, since it’s not a simple button press.
All good. Ride on! (with the light, if you can!)