is waking up in the middle of the night usually caused by hormone issues or a neurological issue?

Waking up at night is age related. Not being able to fall back asleep is a different issue. I can tell you what I do. I have podcasts on my ipod, and a sleep band with flat ear pieces that don't hurt to sleep on- plus the band functions as an eye shade. I put on a podcast (you can set it to turn off after a certain number of minutes) and listen to the podcasts to distract my mind from what we call "monkey brain". Or you can listen to music, and there are specific choices that are supposed to lull your brain to sleep. Exercise helps me sleep better, and stretches before bedtime have been shown to lead to better sleep. 

It's actually natural.  Humans' natural, pre-industrial sleeping pattern is bipartite with a waking period in the middle of the night.  Electric lighting disrupted it for most people but in some of us it's so strong that it's unchangeable.  There's an interesting book on the history of sleep called "At Day's Close: Night in Times Past" that discusses this, not that it will help you sleep, but it might help you feel like you're not suffering from some unique condition.

Try to re-arrange your life to go to bed much earlier and you'll probably find that you'll get in at least an hour longer before waking up.  Then, once you do wake up, don't fight it.  Ben Franklin used his nightly waking period for most of his writing.  It's important to avoid screens though or that will mess up your ability to get back to sleep.  Not easy in this age.  You should then hopefully be able to get 2-4 hours more sleep after the waking period by gradually making bedtime earlier.

Neither. It's psychological.