Custom-fitted earplugs are AMAZING, especially for sleeping. I had a pair of SleepSound earplugs made for me 4-ish years back and have worn them every night since.
They still fit perfectly! Also, I give them a gentle wash with soap and water every morning (almost like I'm washing my hands normally, but with the earplugs cupped between them—takes 30 seconds) and leave them out to dry, so they haven't gotten nasty from a thousand nights lodged in my ears.
They're molded exactly to my ear shape, so by the time I wake up they've formed a seal with the ear canal and it actually takes a bit of effort to pry them out. No amount of tossing/turning/thrashing/getting up in the middle of the night for a glass of water dislodges them.
They still fit perfectly! Also, I give them a gentle wash with soap and water every morning (almost like I'm washing my hands normally, but with the earplugs cupped between them—takes 30 seconds) and leave them out to dry, so they haven't gotten nasty from a thousand nights lodged in my ears.