I came across this one by chance. According to quantum physics everything in the universe is energy. Everything in the universe only differs by degrees of energy. So far the difficult stuff.
Gregorian Chants calibrate very high, very close to the level of Enlightenment (according to Dr. David Hawkins: Power vs. Force; very interesting book about everything in the universe).
Take any CD with Gregorian Chants. And play it in the background that you ‘just about don’t hear it’. So it is there, however it is not overpowering. You will notice that you can study now for very prolonged periods of time. I cannot explain it, however you get a lot less tired, and you are creative on a higher level. That does sound hippie-ish. However simply give it a go.
It is not important if you like those chants or not. Their (high) energy level is important of your liking or not.
Again, a very powerful tool. Personally I have 6 different CDs on the computer. Every Monday I play CD 1, Tuesday I play the second CD and so on. Just to vary and counterbalance the repetitive element.
And: If you like that kind of thing: you might try out the music by Robert Gass (Kyrie and Halleluja). When I heard it the first time I was somewhat disappointed as it seems ‘non-eventful’. However (again to Hawkinds) this is the music with the highest calibration ever. It is safely in the realm of Enlightenment (if you are interested in that). This has nothing to do with Study Skills as such, however should you have a physical ailment: Listen to one piece (= 26 minutes) per day, and you will find that your problems – quite magically – go away. I can’t explain it (logically). However I do know that it works. I tried it out often enough by now. Anyway, the energy is so high that it is way beyond the logic realm.
On a more practical level: what do you got to lose? Give it a go, and see what happens.