as embodied and broadly described herein , the disclosures herein provide detailed embodiments of the invention . however , the disclosed embodiments are merely exemplary of the invention that may be embodied in various and alternative forms . therefore , there is no intent that specific structural and functional details should be limiting , but rather the intention is that they provide a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present invention fig1 depicts an embodiment of a king size fitted sheet 100 . fig2 depicts an embodiment of a queen size fitted sheet 200 . fig3 depicts an embodiment of a full size fitted sheet 300 . fig4 depicts an embodiment of a twin xl size fitted sheet 400 . fig5 depicts an embodiment of a twin size fitted sheet 500 . the embodiments of the different sized fitted sheets shown in fig1 - 5 have similar design with different sizes and fixture placement to accommodate the corresponding sized bed . therefore , the description of fig1 also applies to fig2 - 5 . the sheets disclosed herein may be comprised of any fabric , for example , cotton , wool , silk , burlap , felt , bamboo , hemp , nylon , linen , polyester , polypropylene , other cloths , other naturally occurring or manmade materials , and combinations thereof . in the preferred embodiment , fitted sheet 100 is comprised of a flat top portion 105 and side portions 110 a - d . side portions 110 a - d preferably extend perpendicularly from flat top port 105 and are adapted to envelope the sides of a mattress . for example , as shown , side portions 110 a and 110 c have a length that corresponds with the length of the head and the foot of the appropriate mattress ( king size in the example shown in fig1 ). similarly , side portions 110 b and 110 d have a length that corresponds with the length of the sides of the appropriate mattress ( king size in the example shown in fig1 ). side portions 110 a - d preferably all have a depth that can accommodate multiple depth mattresses . for example , side portions 110 a - d may be 10 ″ in depth , 12 ″ in depth , 15 ″ in depth , 17 ″ in depth or another depth . preferably , the edge of side portions 110 a - d that is opposite the edge that is attached to top portion 105 has a securement device 115 that is adapted to removably secure fitted sheet 100 to a mattress . the securement device 115 may be elastic , adhesive , ties , snaps , buttons , toggles , another device , or combinations thereof . in the preferred embodiment , fitted sheet 100 is adapted to be placed on top of a mattress and side portions 110 a - d are adapted to envelop the sides of the mattress with the ends of side portions 110 a - d being secured under the mattress . preferably , side portion 110 c , which is preferably the foot of fitted sheet 100 has one or more sheet coupling devices 120 a - d . while four sheet coupling devices 120 a - d are shown there can be more or fewer sheet coupling devices . for example , fitted sheet 100 may have 2 , 3 , 5 , 6 or another number of sheet coupling devices . in the preferred embodiment , all of the sheet coupling devices are positioned along the foot portion of fitted sheet 100 . by positioning all of the sheet coupling devices along the foot of fitted sheet 100 , the sheets preferably will not restrict movement of the bed user into and out of the bed especially during an emergency . however , it is possible to position sheet coupling devices along the sides of fitted sheet 100 and / or along the head of fitted sheet 100 . preferably , each sheet coupling device is positioned within the side portions 110 a - d , however sheet coupling devices may be positioned on the top potion 105 of fitted sheet 100 . each sheet coupling device is preferably at least one of a button , a button hole , a male or female portion of a snap closure , a grommet , a tie or tassel , adhesive , or another fastening device . preferably , coupling device is a temporary device that is able to couple and uncouple the sheet set as desired , yet is capable of maintaining the sheets in contact during use . however , in other embodiments , the sheets are permanently coupled together . in embodiments where the coupling device is a button hole , a grommet , or another type of hole , the hole may be reinforced with extra fabric or another material . additionally , the hole edges may be secured to prevent fraying , for example , with thread . in embodiments where the coupling device is a button hole , a grommet , or another type of hole , a toggle , button , or other device may be inserted into the hole to secure the top sheet to the fitted sheet . the toggle , button , or other device may be coupled to the top sheet or may be adapted to be inserted into holes in both the fitted sheet and the top sheet . the securement device may resemble a cufflink . for example , the device may have one fixed portion and one movable portion , two fixed portions coupled by a chain , rope , or other flexible device , or may be unmovable . the securement device may be made of fabric , metal , plastic , wood , or other manmade or naturally occurring materials and combinations thereof . fig6 depicts an embodiment of a king size top sheet 600 . fig7 depicts an embodiment of a queen size top sheet 700 . fig8 depicts an embodiment of a full size top sheet 800 . fig9 depicts an embodiment of a twin xl size top sheet 900 . fig1 depicts an embodiment of a twin size top sheet 1000 . the embodiments of the different sized top sheets shown in fig6 - 10 have similar design with different sizes and fixture placement to accommodate the corresponding sized bed . therefore , the description of fig6 also applies to fig7 - 10 . the sheets disclosed herein may be comprised of any fabric , for example , cotton , wool , silk , burlap , felt , bamboo , hemp , nylon , linen , polyester , polypropylene , other cloths , other naturally occurring or manmade materials , and combinations thereof . in the preferred embodiment , top sheet 600 is comprised of a single piece of material 660 with an extension 665 at the foot of the sheet . preferably piece of material 600 is as long as the corresponding mattress . for example , piece of material 660 is preferably 80 ″ long to accommodate the 80 ″ length of a king size bed . however , piece of material 660 can be longer or shorter than the corresponding mattress . preferably , the width of piece of material 660 is wider than the corresponding mattress such that that the sides of piece of material 660 can be tucked around and under the sides of the mattress . however , piece of material 660 can be as wide as he corresponding mattress or shorter than the corresponding mattress . preferably extension 665 is sewn onto the foot of piece of material 660 . however , extension 665 can a continuous extension of piece of material 660 , can be fastened with adhesive , staples , buttons , snaps , ties , another fastening device , or combinations thereof . preferably , extension 665 is not as wide as the width of piece of material 660 , thereby providing cutouts 670 a and 670 b . cutouts 670 a and 670 b preferably allowed top sheet 600 to lay flat on top and along the sides of a mattress without bunching and / or overlapping in the corners . in the preferred embodiment , extension 665 is long enough to cover the foot of a mattress ( i . e . is as long as the depth of the mattress ). however , extension 665 can be longer or shorter than the depth of the mattress . preferably , extension 665 has one or more sheet coupling devices 675 a - d . while four sheet coupling devices 675 a - d are shown there can be more or fewer sheet coupling devices . for example , extension 665 may have 2 , 3 , 5 , 6 or another number of sheet coupling devices . preferably , the number of sheet coupling devices 675 a - d is equal to the number of sheet coupling devices 120 a - d . in the preferred embodiment , all of the sheet coupling devices are positioned within extension 665 . by positioning all of the sheet coupling devices within extension 665 , the sheets preferably will not restrict movement of the bed user into and out of the bed especially during an emergency . however , it is possible to position sheet coupling devices along the sides of piece of material 660 and / or along the head of piece of material 660 . preferably , the positioning of the sheet coupling device within top sheet 600 corresponds to the positioning of the sheet coupling device within fitted sheet 100 . sheet coupling devices may additionally be adapted to couple a blanket or quilt to the fitted sheet and / or the top sheet . for example , fig1 depicts an embodiment of a comforter 1100 having holes 1180 a - d into which sheet coupling devices can be placed . comforter 1100 may be used with or without a top sheet . while four holes 1180 a - d are shown there can be more or fewer sheet coupling devices . for example , there may be 2 , 3 , 5 , 6 or another number of holes . preferably , the number of holes 1180 a - d is equal to the number of sheet coupling devices 120 a - d . preferably , the positioning of the holes within comforter 1100 corresponds to the positioning of the sheet coupling device within fitted sheet 100 . similarly , a duvet cover 1200 , as shown in fig1 , may be coupled to the sheet coupling devices . the duvet cover 1200 may have holes 1290 a - d into which sheet coupling devices can be placed . as shown , holes 1290 a - d may be positioned in an extension 1295 of the duvet cover 1200 . for example , the duvet may be placed into the duvet cover 1200 through slot 1298 and extension 1295 may extend beyond the slot . preferably , duvet cover 1200 and extension 1295 are made of the same material . duvet cover 1200 may be used with or without a top sheet . while four holes 1290 a - d are shown there can be more or fewer sheet coupling devices . for example , there may be 2 , 3 , 5 , 6 or another number of holes . preferably , the number of holes 1290 a - d is equal to the number of sheet coupling devices 120 a - d . preferably , the positioning of the holes within duvet cover 1200 corresponds to the positioning of the sheet coupling device within fitted sheet 100 . other embodiments and uses of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein . all references cited herein , including all publications , u . s . and foreign patents and patent applications , are specifically and entirely incorporated by reference . it is intended that the specification and examples be considered exemplary only with the true scope and spirit of the invention indicated by the following claims . furthermore , the term “ comprising of ” includes the terms “ consisting of ” and “ consisting essentially of .”