Flat sheet providing fitted mattress engagement

A sheet apparatus comprising:

• a bottom sheet, said bottom sheet adapted to engage upon a mattress where said mattress has a top surface surrounded by a sidewall where said sidewall extends a sidewall distance to a bottom surface of said mattress;
• said bottom sheet having a body, said body having a body area which is planar, said planar body area extending to a perimeter edge of said body;
• said bottom sheet having a bottom surface positionable upon said top surface of said mattress, and having a top surface opposite thereto;
• said bottom sheet having four corners at said perimeter edge of said body which are not sewn to pockets;
• said body having a rectangular central area with four corners thereof;
• edge portions of said body, said edge portions extending for an edge width from a perimeter edge of said central area, to said perimeter edge of said body;
• four biasing bands, each of said biasing bands having a central portion, said central portion extending between two opposing ends which are secured upon top surface of said body at securement positions adjacent said perimeter edge of said central area;
• each of said four corners of said rectangular central area having one respective central portion of a respective said biasing band, extending thereover;
• and
• each respective central portion of each biasing band stretchable to a respective biased engagement at a respective corner of said mattress, said biased engagement positioning said central portion of said biasing band in a removable biased contact against said top surface of said sheet thereby holding said bottom surface of said sheet in biased contact with both said sidewall and said bottom surface of said mattress.