Sometimes it’s hard to know when our mattress has gone bad: it isn’t always the most obvious thing. A bad mattress isn’t out knocking over bed and breakfasts or robbing bedroom furnishing stores. In fact, it has an air tight alibi: it was in your house the entire time.

Still, there are ways to tell when your mattress has gone to the dark side. Perhaps you’ve fluffed it up to no avail, or maybe you’ve moved it around with no result. Perhaps it used to be white and now is brown or maybe you’ve flipped it so many times that now you just want to flip it off. Perhaps your mattress completely falls apart or maybe one of the following things happens:

It get saggy: We all know that things sag with age. Unfortunately, a mattress is not immune to gravity’s cruel joke.  Mattresses tend to sag regardless, but their sagginess increases drastically with use. If you end up sleeping on the floor while still in bed, or the middle part of your mattress resembles a black hole (and you haven’t seen your spouse for a week) it’s time to let your mattress go. When your mattress goes from saggy to too saggy, it’s time to throw out the old for the new.

It’s too hard: It’s too hard, it’s too soft, it’s just right. Rating your mattress in this manner may make you feel like one of Goldilocks three bears, but a mattress that is too hard can hardly be one right for you. Instead of suffering at night and – in the form of a sore back – suffering in the morning, buy a mattress that you actually look forward to sleeping on. Firm is good, but too firm tends to be bad: no one, not even the three bears, wants to sleep on a board.

The coils are always happy to see you: It’s nice to be loved, but when bed coils are so happy to see you that they continually stab you in the front, in the back, and everywhere in between whenever you make the slightest movement in bed, it’s time to move on. Old mattresses tend to have coils that have sprung loose, making an uncomfortable night for anyone in their path. Because these loose coils can’t simply be removed, the entire mattress has got to go.

It’s squeaky: Sometimes the squeaky wheel gets the grease and sometimes it gets replaced. When it comes to squeaky mattresses, they should always be replaced. No amount of WD40 is going to keep your mattress quiet, at least not for long. If you find that your mattress makes so much noise that it keeps you up at night, or interferes with your REM cycle, kindly escort it to the nearest trash can.

Um, you can’t sleep: If allergy woes, back problems, or just plain old discomfort keep you from sleeping, it’s time to bid your old mattress goodbye and opt for something better. Latex mattresses can help with allergies while foam and air mattresses can help with soreness. These recent innovations in mattresses make sure that we sleep how we were meant to: in complete and total comfort.