No matter what type of mattress you own, the general rule of thumb is they are ready for replacment every 7-10 years. This all depends on how a mattress is maintained and much it is used and by how many people. Another large factor is how clean your mattress is kept, by using a the correct type of protector you can help keep bed bugs, dust mites and dead skin to a minimum.
Over time depending on how well your mattress is maintained it becomes a breading ground for little dust mites and allergens, these are not visable to the naked eye. We can spend up to 8-10 hrs per day sleeping in our beds and your mattress over time collects sweat and deposits from our body/skin. Your mattress can actually double in weight over 10 years. There for it is important to keep you mattress up to date and change. eg. A hospital mattress is always sterilised whenyou leave hosptial.