We sell mattresses, so you would expect us to say you need a new one. What we actually say, several times a week, is that the mattress is fine and the base underneath it is the problem — or that somebody is about to replace a perfectly good bed because of a figure they read somewhere.

So here is the honest answer to how often you should change your mattress: the usual advice is every seven to eight years, and that is a sensible place to start thinking rather than a deadline. What matters far more is how it was made, what it sits on, and how you have been sleeping lately.

The seven to eight year rule, and why it is only a rule of thumb

Seven to eight years is the figure the trade generally quotes, and as an average across all mattresses and all households it is about right. The trouble is that almost nobody is average.

Four things move the number more than age does:

Which is why we would rather you judged the bed you have than counted the years since you bought it.

Six signs you need a new mattress

These are the ones that genuinely mean something, roughly in order of how much weight we would put on them.

1. You wake up with aches you did not go to bed with

Stiffness in the lower back or hips that eases within an hour of getting up is the most commonly reported sign, and the one worth taking seriously. If it has come on gradually over a year or two rather than suddenly, the bed is a reasonable suspect. If it came on suddenly, or it does not ease, that is a conversation for your GP rather than a furniture shop.

2. You sleep better away from home

This is the most telling sign of all and the one people mention last, usually as an aside. If you consistently sleep better in a hotel, or in the spare room, your own mattress is not doing its job. Nothing else tells you as plainly.

3. You can see it

Strip the bed and look along the surface from the side, at eye level, with a light behind it. Dips where each of you sleeps, a ridge up the middle, or a visible sag tell you the fillings have compressed and are not coming back. If you and your partner roll towards each other in the night without meaning to, that is the same thing felt rather than seen.

4. You can feel the structure

Feeling individual springs, or a hard edge under the fabric, means the fillings above them have given up. Sitting on the edge to put your socks on and feeling it collapse is the same message.

5. It has started making noise

New creaking or twanging is worth investigating, though check the base first — a surprising amount of bed noise is a loose base or a frame moving on a hard floor, not the mattress at all.

6. You cannot remember buying it

Not scientific, but reliable. If nobody in the house can say with any confidence what year it arrived, it is almost certainly old enough to be worth assessing properly.

If you consistently sleep better in a hotel than at home, nothing else needs to be said.

The myth worth ignoring

You will have seen the claim that a mattress doubles in weight over the years through accumulated dust mites and skin. It gets repeated constantly, usually by people selling mattresses, and there is no good evidence for it.

We would rather not sell beds that way. A washable mattress protector, changed and laundered like any other bedding, and airing the bed properly in the morning instead of making it immediately, deal with the real hygiene question perfectly well. Replace a mattress because of how you are sleeping on it, not because of a statistic designed to alarm you.

Check the base before you blame the mattress

This is the part that gets missed, and it is the reason some people replace a mattress twice in five years and never work out why.

A mattress can only hold the shape of what it sits on. A divan base with a sagging platform, or a wooden frame with bowed or cracked slats, passes that shape straight into whatever you put on top of it. Fit a new mattress to a tired base and you have bought the old dip at full price.

Worth checking: press firmly across the base with the mattress off and feel for softness or give; look along the slats for bowing, and check the centre rail and its legs if there is one; make sure nothing has worked loose. Bear in mind too that many mattress guarantees expect a sound, supportive base underneath, so it is worth reading yours.

If the base is the same age as the mattress, the honest answer is usually to replace both together. Our guide to divan bases, ottomans and frames explains what each type does, including how a platform top or a sprung edge changes how a mattress feels.

How to get more years out of the one you have

If the bed is sound and you are simply hoping to delay the expense, three things genuinely help:

• Rotate it head to foot every three to six months, so the same areas are not always under the same weight. Most modern mattresses are not designed to be flipped over — check the label before you try.
• Use a washable protector. It keeps moisture and marks out of the fillings, and it is far easier to launder than a mattress is to clean.
• Let it air. Pull the covers back for half an hour in the morning rather than making the bed straight away. In a Highland winter, with the heating on and the windows shut, that half hour matters more than it sounds.

What to do with the old mattress

Mattresses are awkward to get rid of, which is why so many end up propped in a garage for a year. Three realistic routes:

• Ask your retailer. Some will take the old one away when they deliver the new one, often for a fee, and it is much the easiest option if it is available. Ask when you order rather than on delivery day, since it usually has to be arranged in advance.
• Your local authority. Councils run bulky uplift collections and household waste recycling centres; charges and booking lead times vary, so check what your own council offers before you commit to a date.
• Reuse, if it is genuinely fit for it. Charities and reuse schemes can only accept mattresses that are clean, undamaged and still carry their fire-safety label. If yours has dips in it, it is not a kindness to pass it on — recycling is the better answer.

Mattress replacement FAQ