I do this ALL the time, literally! Thought I was the only one! Since I was a kid, I have this weird need to be listening to something as I go to sleep. Music never really works for me, so it ends up being talking of some kind usually. I didn't like the political right wing talk, so I grew up listening to Art Bell on Coast to Coast AM. But even that gets old. So I used to hold a cassette recorded up to the TV speakers and record the audio off of VHS tape playbacks to listen to later. A lot of episodes from TOS and TNG work really well as audio dramas, especially if you're a Trek fan and have the sets and actors/characters already in your mind's eye.
Nowadays, in the world of streaming Netflix on your smartphone, and with unlimited data caps or unlimited wifi caps, You can stream all of the episodes from all of the series on Netflix. I listen to Trek almost every night as audio plays, streamed through Netflix, and I love it. It really adds a different aspect to the series, and helps you to catch little vocal nuances that you didn't before. Cool stuff!