Custom-made ear plugs. Even if you only wear ear plugs occasionally (I do when in a noisy hotel, or when a neighbor goes a bit too crazy), they are so worth having.
Basically you go to an audiologist and they put something kinda liquid in each of your ears to take a mold of your ear canals. A couple of weeks later, you have plastic earplugs that have the exact shape of your inner ears.
Upsides: • They work, always. I would typically use wax or silicon disposable ear plugs before that, and sometimes in the middle of the night they might move and let the sound in; those don’t. Also, foam disposable ear plugs don’t stay in my ear, don’t ask me why. • They never hurt. Since disposable ear plugs get shoved into your inner ear until they take the shape, they continuously push against the walls of your ear canals. I would often feel kinda bruised after using them for a long time. • They are crazy comfortable. Put your ear on a pillow, and you barely feel them at all. • But do they block too much sound? That’s up to you. Basically, you choose the level of noise you want to keep out, which I believe is achieved by using different kinds of plastic.
They’re not a trivial purchase (I think mine cost $150), but then you use them for decades, so it’s definitely worth it. It was a stupid purchase in my case, because I bought them on a whim out of anger against my neighbor’s party one night; but they’ve followed me everywhere since!