1) try noise cancelling headphones
NO: they have undefinable effects on your psyche. Maybe "pressure" or some sort of non-silent silence that your body still reacts to?
2) white noise, pink noise, music, classical music, new age music, atmospheric sounds, etc
NO: actually, these are similar to noise-cancelling headphones. Your brain is still reacting to the sound in a non-passive way.
3) giant earmuffs
NO: heavy, physical head pressure, etc
solution) 3M ear classic NRR 33 earplugs. when I need to concentrate. while sleeping. Keep a pair around for "that guy" playing videos on his phone in public. The BEST. I buy 200 at a time.
After reading this article, I wonder if noise-cancelling headphones + 3m earplugs might work together?