"A ten year old mattress weighs double what it did when it was new, because of the -ahem- debris which is absorbed through the years. That debris includes dust mites (their droppings and their decaying bodies), mold, millions of dead skin cells, dandruff, animal and human hair, secretions, excretions, lint, pollen, dust, soil, sand and a lot of perspiration, of which the average person loses a quart per day. Good night!"