Memory foam might have been created by NASA, but knowing when to swap out your mattress is not rocket science. If you’re not getting a good night’s sleep, likely something is keeping you awake. Of course, stress, a partner who tosses and turns, traffic noise, and a host of other things could be keeping you awake. But the typical offender is a worn-out mattress. If your sleep surface is lumpy and saggy, it may be the cause of your insomnia. Our spines and necks rest most naturally on a mattress that gives consistent support in all the right places. And once the body is at rest, our brains find it easier to fall asleep. Lumpy mattresses keep people awake; it’s that simple.

Try it out: Run your hands across your mattress. Is it lumpy? Does it sag? If the answer is yes, then it is time for a change.

Deep, restful sleep is incredibly important for our physical and emotional well-being. Everyone can comprehend the irritability and distress that occurs when someone is overtired. But fatigue can be a mystery if you have slept for the recommended eight or nine hours. If you can secure a good quantity of sleep, but still feel tired, it may be your sleep quality that is suffering.

Your mattress may be the culprit. As mentioned a section above, lumps and sags can cause discomfort. In turn, this can cause the brain to focus on the body, rather than on its sleep cycle. However, if your mattress has a consistently comfortable sleep surface, you may still want to consider its level of firmness. Back sleepers often need a medium (or firmer) mattress. Stomach sleepers usually prefer a firm bed.

Ask yourself: Do you feel like you could fall back asleep three or four hours into your day? That could be your body telling you that you didn’t get the quality of sleep you needed.

Ignorance is bliss. Perhaps you sleep like a baby night after night on a bed you’ve loved for decades. But your partner may not. Sleep patterns differ from person to person. And if your partner is losing sleep, that is something that needs to be taken seriously. In fact, if your spouse’s sleep worsens, that may have a second-hand effect on you. The more uncomfortable your mattress becomes through wear, the more your partner may toss and turn. You might sleep through all this, but your brain will be somewhat aware of your partner’s nocturnal movements. In time, this will affect your sleep quality. The best and easiest solution is to replace an aging mattress when your sleep partner says it’s time.

Ask yourself: Does whoever you share a bed with sleep restlessly? Do they describe your mattress as uncomfortable?

Is your mattress causing you pain? It can be hard to know whether your back pain is caused by your sleep patterns or other factors. Most likely it’s an interaction of several factors over time. Sitting at a desk all day can tighten your hips and cause a slumping posture that strains your neck and shoulders. Likewise, many folks in physically taxing jobs put a lot of stress on their backs and joints every day. So how do you know if your mattress is the problem? Well, taking note of when the pain is most acute, or when it first occurs, is a good start. Do you wake up in the night with back pain? Is it there first thing in the morning, or does it develop during the day?

If the pain seems more pronounced during the night, your mattress may not be providing the support or relief that your sleep position requires. For example, if you sleep on your back, and your mattress is soft, your lower back may not be properly supported. Understanding your sleep position and the mattress types that are best suited to you will help you shop wisely. (Read our top picks for back, stomach, and side sleepers.) And remember, if you have chronic or severe pain, seek medical advice before shopping for a new mattress.

Ask yourself: When are your aches and pains worst throughout the day?

There are some great mattress toppers on the market right now that can adjust firmness with remarkable effectiveness. A well-chosen pillow can improve your sleep quality dramatically, especially if neck pain is your chief concern. And don’t be afraid to experiment with different duvets. Comfort is a subjective matter, and there are several low-cost ways to enjoy your bed more. Maybe all you need is a pair of earplugs if the ambient noise in your neighbourhood is particularly bothersome. Struggling to fall asleep or struggling to stay asleep is not always indicative of a hopeless mattress. Knowing when not to replace a mattress is part of knowing when to replace a mattress. Try thinking outside the box first. All the cost savings could add up over time.

Ask yourself: Have you tried adjusting the comfort level of your bed with a mattress topper, pillow, or new bedding?