How often you should wash your bed sheets? We spend more than a third of our lives in bed - but that place can quickly blossom into a "botanical park" of bacteria and fungus. If left for too long, the microscopic life within the wrinkles and folds of our bed sheets can even make us sick.

To stem the invisible tide, he said sheets should be washed once a week. Humans naturally produce roughly 26 gallons of sweat in bed every year. When it's hot and humid outside, this moisture becomes what scientists call an "ideal fungal culture medium."

A bed sheet is a rectangular piece of cloth used as bedding, being placed immediately below or above bed occupants. Bed sheets can generally be divided into two categories: "top" and "bottom" sheets.

A bottom sheet is laid above the mattress and bed occupants lie on it. It may be either a flat sheet (extra fabric is usually tucked under the mattress), or a fitted sheet, which is sewn in a pocket-like shape to go down over the corners of the mattress, and has an elastic band around the edges of the sheet to prevent the sheet from slipping.

A bed sheet is a rectangular piece of cloth used as bedding, being placed immediately below or above bed occupants. Bed sheets can generally be divided into two categories: "top" and "bottom" sheets.

A bottom sheet is laid above the mattress and bed occupants lie on it. It may be either a flat sheet (extra fabric is usually).