Something semi ambient, preferably without lyrics: Tycho, Bonobo, Nujabes

I like any of the Nujabes albums. He makes chilled, mainly instrumental, hip hop music.

Here's a tip I picked up somewhere. Make a playlist. An hour or two worth of music. ONLY listen to it when you're studying. I've found my brain just blocks it out after a few times through, but it triggers my subconscious or something. As in, if I'm not feeling like studying, I put it on and my brain just goes,"OK, it's time to study." I change it up when I'm starting a new long task (writting a new book, starting a new semester, whatever). At first, I find myself listening to it, but it doesn't take much repetition for it to fade into the background.

Robot Science

Any rando lofi channel on YouTube/Spotify/Online Radio Stations

Piano Phase by Steve Reich

Every album by the band Can

Battlestar Galactica OST by Bear McCreary

then either their Piano Nights or Black Earth. Slow darkjazz that sets up an atmosphere and doesn't distract that much.

Anything by Erang. If you are into medieval mythical themed hymns.

Autechre's NTS Sessions. All of them work great, but start with the fourth one.

In a Space Outta Sound by Nightmares on Wax

Not really a album but MyNoise.net has a lot of good generators for background noise. Radio Free Fedi's Comfy channel also is great for chill study music, and it only plays indie artists that have Fediverse accounts with links to the artist support pages where you can either buy their albums (or songs to build your own piecemeal) https://radiofreefedi.net/.

I just added a bunch of classical to a playlist and then removed the occasional piece I found distracting. I still use that playlist when I need to focus.

Bonobo - Dial M for Monkey

Don’t do albums or long playlists, because every time it ends you’ll realize time has passed and you’ll stop studying. Instead pick a song or two or three and just play on repeat so you lose track of time. But if you must, then Toxicity by System of a Down.

Use something mellow in a different language from your own, it is less distracting.

I like to listen to brasilian Bossa Nova like this Getz/Gilberto Album

Or something without lyrics like Yiruma if you like Piano music.

Anything from Hammock. The older albums mostly.

Anything by Kiasmos. Also Chopin.

There came an echo by big giant circles.

Bit of of left field here: The going under OST. Was the soundtrack to my exams

Jan Garbarek - Visible World

Nils Frahm's Felt, or the soundtrack to Victoria

Atomos or the self titled album by A Winged Victory for the Sullen

Almost anything recent by Carbon Based Lifeforms but Alt:01, Alt:02, or Stochastic especially

Loscil is great but not a single album stands out though Submerz and Endless Falls are smooth

Hammock's soundtrack for the movie Columbus

Brian Mcbrides The Effective Disconnect

I would recommend Stars of the Lid, but they are too sleepy for me. However, when Brian Mcbride and Adam Witzie do their own thing it is usually less sleep inducing-

Little Songs About Raindrops - Lullatone