The term MATTRESS ANNOYANCE can be broken down into two crossword solutions: SAG (3 letters) and LUMP (4 letters). A mattress annoyance is a common problem that can occur with mattresses, such as sagging or lumpiness. Sagging occurs when the mattress loses its shape and becomes uneven, while lumpiness is caused by lumps or bumps in the mattress. Both of these issues can cause discomfort and make it difficult to get a good night's sleep.