What is this weird strange anxiety I've been feeling every night? Grown up answers only...?
My first guess is sleep apnea. That's were you stop breathing in the middle of the night. Breathing is so basic that it can send you body into a panic mode. The doctor will have you do a sleep study, and then they'll get you a cpap machine. It just blows air into your nose. You probably also have mild anxiety. Meditation and mindfulness can help. Mindfulness is too hard to explain here, but there are some good youtube videos about it. You need to see the doctor for the sleep apnea. If left untreated it can cause other problems that are a big deal.
I am in the same position as you (mostly by choice) and I recall something like that happening to me. If it turns into real anxiety, put a drop of Camomile Roman essential oil on a tissue at the side of your pillow at night. That will get rid of it.