Made up of initial body support (male and female average, 30%), change in body support over time (25%) stabilisation (15%), change in height and firmness (10%) permeability (10%) fatigue (5%), smell (new and fortnight average, 5%).
Using an oscilloscope we measure the movement of the mattress after a standard impact (17.5kg), simulating the turning body of a sleeping person. We also count the number of bounces up and down before the mattress is calm again. Higher-scoring mattresses exhibited fewer bounces and less movement during standard impact.
We roll a cask-shaped roller over each mattress for 30,000 cycles to simulate usage of approximately eight years. Then, we measure height and firmness straight out of the box, and again after this test to note any differences. The lower the score, the greater the difference.
We roll a cask-shaped roller over each mattress for 30,000 cycles to simulate approximately eight years' use. Visible damage such as cracking, broken springs or pilling contributes to fatigue score. A higher score means less damage.
If applicable. Bed in a box brands offer home trial periods that range from 30 to more than 100 nights. If you're unhappy with your purchase, you can exchange the mattress for a different model (if available) or a full refund.