Fire up youtube and start playing a documentary and keep it playing all night, and have it set to autoplay. YouTube premium or revanced to keep the screen off while audio plays. I recommend llong form comtent, and prefer documentaries about the cosmos, something like videos from the yt channel Astrum or Kurzgesagt.
Cheap and works 100% for me! Play some lighthearted content though, as whatever the narrator speaks makes it to your dreams/REM phase occasionally lol