Why for the life of me I can’t stay awake when listening to Music?

Change your chair its probably so comfortable that along with some great music you relax completely into sleep. So a hard chair and no way to put your legs up. I know as I quite often suffer the same sleepiness and napping as you. Its really disconcerting to enjoy tracks one to three and then awake at number 8. Its also about the state you sit down to listen. However I’d say your system must be organic and warm so nothing to worry about there.

Just go with the flow.  If you are getting enough rest and still not staying awake maybe it’s time for a change.  Maybe even to a different pastime if needed. 

Easy fix. Espresso and AC/DC.

Um, actually I'd suggest maybe you normally feel much more anxious than you realize.  Worth talking to an expert, but if you normally run with constant interruptions, from task to task, and then stop, then music is your signal to stop all that, but you are already overtired. 

The solution may be to find ways to be less wound up during the day.  Always, and I mean, always, reach out to a professional like a therapist who are really super nice and have a lot of tips you'd never think of. 

@OP If your system puts you to sleep at any time of the day, I'd get a health check.

If it makes you drowsy in the evening, that may just be the music putting you in a relaxed state and hastening you sleep - and nothing wrong with that at all.

Before the advent of screens, it used to be that reading or listening to relaxing music were normal pre-sleep routines.