Patent Publication Number: US-2023157455-A1

Title: Bed Systems and Methods

Description:
RELATED APPLICATIONS 
     This application (Attorney&#39;s Ref. No. P220332) claims benefit of U.S. Provisional Application Ser. No. 63/282,632 filed Nov. 23, 2021, the contents of which are incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     This application relates to bed systems and methods and, in particular, to bed systems and methods that facilitate face down sleeping. 
     BACKGROUND 
     Bed systems typically include a mattress sized and dimensioned to support a lying person (hereinafter “the user”). A mattress typically takes the shape of a rectangular pad defining a sleep surface and comprising a case and filler material arranged within the case. The sleep surface is typically generally planar. The case is typically made of heavy cloth, and the filler may be made of one or more materials selected to comfortably support the lying person such as hair, straw, cotton, wool, foam rubber, and/or a framework of metal springs. Mattresses are typically sold in a predetermined sizes such as single/twin, double/full, queen, and king and in varying thicknesses. The case and filler of a typical mattress typically form a system that cannot practically be cut or otherwise modified. 
     Typically, but not necessarily, the mattress is supported by a bed base, such as a support box or slatted foundation. The bed base supporting the mattress is typically the same size as the mattress. Most bed bases are configured to support the sleep surface in a substantially horizontal arrangement. The bed base typically incorporates or is supported by a bed frame. Bed frames are typically metal, wood, or a combination of metal and wood. Bed frames may be sold in a size compatible with the mattress and/or base or may be reconfigured to support two or more mattress sizes. Bed frames may also be configured such that the sleeping surface may be adjusted to a desired height relative to the floor surface supporting the bed system. Paired with an appropriate mattress, certain bed bases are adjustable to allow one or more portions of the sleeping surface to be angled with respect to horizontal. 
     Bed systems are sold in a number of configurations designed to accommodate the sleep preferences of different users. Some users prefer a soft bed, while others prefer a firm bed. Bed systems for a child may be smaller (e.g., single, double, or full size), while bed systems for two users are typically larger (e.g., queen or king size). 
     Sleeping on one&#39;s stomach on conventional mattresses no matter the head position, puts large amounts of stress/strain on our neck, head, jaw, shoulders, mid back, and surrounding soft tissues (e.g., muscles, tendons, ligaments, fascia). It can even have negative effects on vessels and nerves. All these effects are amplified after neck injury. 
     The need exists for bed systems and methods configured to accommodate users who prefer to, or must, sleep face down. 
     SUMMARY 
     The present invention may be embodied as a bed system for supporting at least one user in a face down orientation, the bed system comprising a mattress system and a base system. The mattress system defines at least one sleeping surface and at least one opening. The base system is configured to support the mattress system such that a fresh air space is formed under the opening. The mattress system is configured to support the at least one user in the face down orientation with at least a portion of the at least one user being arranged within the at least one opening. 
     The present invention may also be embodied as a method of supporting at least one user in a face down orientation, the method comprising the following steps. A mattress system defining at least one sleeping surface and at least one opening is provided. A base system is arranged to support the mattress system such that a fresh air space is formed under the opening such that the at least one user may be supported in the face down orientation with at least a portion of the at least one user being arranged within the at least one opening. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a top perspective view of a first example bed system of the present invention; 
         FIG.  2    is a bottom perspective view of the first example bed system; 
         FIG.  3    is a side elevation view of the first example bed system of the present invention; 
         FIG.  4    is a top plan view of the first example bed system of the present invention; 
         FIG.  5    is a side elevation view of a second example bed system of the present invention; 
         FIG.  6    is a side elevation view of a third example bed system of the present invention; 
         FIG.  7    is a side elevation view of a fourth example bed system of the present invention; 
         FIG.  8    is a top plan view of the fourth example bed system; 
         FIG.  9    is a side elevation view of a fifth example bed system of the present invention; 
         FIG.  10    is a top plan view illustrating a variation of the mattress used by any of the first through fifth example bed systems; 
         FIG.  11    is a first side elevation view of a sixth example bed system of the present invention; 
         FIG.  12    is a second side elevation view of the sixth example bed system of the present invention; 
         FIG.  13    is a side elevation view of a seventh example bed system of the present invention; 
         FIG.  14    is a side elevation view of an eighth example bed system of the present invention; 
         FIG.  15    is a side elevation view of a ninth example bed system of the present invention; 
         FIG.  16    is a side elevation view of a tenth example bed system of the present invention; 
         FIG.  17    is a side elevation view of an eleventh example bed system of the present invention; 
         FIG.  18    is an end elevation view of the eleventh example bed system of the present invention; 
         FIG.  19    is a top plan view a first variation of any of the sixth through eleventh example bed systems; 
         FIG.  20    is a top plan view a second variation of any of the sixth through eleventh example bed systems; 
         FIG.  21    is a top plan view a third variation of any of the sixth through eleventh example bed systems; 
         FIG.  22    is a top plan view a fourth variation of any of the sixth through eleventh example bed systems; 
         FIG.  23    is a top plan view a fifth variation of any of the sixth through eleventh example bed systems; 
         FIG.  24    is a top plan view a sixth variation of any of the sixth through eleventh example bed systems; 
         FIG.  25    is a top plan view of a twelfth example bed system; 
         FIG.  26    is a section view along lines  26 - 26  in  FIG.  25   ; 
         FIG.  27    is a top plan view of a thirteenth example bed system; and 
         FIG.  28    is a section view along lines  28 - 28  in  FIG.  27   . 
     
    
    
     DETAILED DESCRIPTION 
     The present invention may be embodied in a number of different forms, and several embodiments of the invention, with variations of each of these embodiments, will be described below. In the following discussion, the term “horizontal” will be used to refer to a plane parallel to true horizontal, the term “vertical” will be used to refer to a plane parallel to true vertical, and the term “lateral” will be used to refer to a direction orthogonal to both horizontal and vertical planes and in a direction orthogonal to a longitudinal axis of any example bed system or example mattress described herein. 
     Referring initially to  FIGS.  1 - 4    of the drawing, depicted at  20  therein is a first example bed system  20  constructed in accordance with, and embodying, the principles of the present invention. The first example bed system  20  comprises a mattress  22  and a base system  24 . 
     The example mattress  22  defines a sleeping surface  30 , an opening  32 , a perimeter surface  34 , and a bottom surface  36 . The example opening  32  extends from the sleeping surface  30  to the bottom surface  36 . In all other respects, the structure of the example mattress  22  is or may be conventional (e.g., case and filler material) and will not be described in further detail. 
     The example base system  24  comprises a support box  40 , a primary frame assembly  42 , and a secondary frame assembly  44 . The example primary frame assembly  42  comprises at least two primary longitudinal frame rails  50 , at least two primary lateral frame rails  52 , and at least four primary frame legs  54 . The example secondary frame assembly  44  comprises at least two secondary longitudinal frame rails  60 , at least two secondary lateral frame rails  62 , and at least four secondary frame legs  64 . 
       FIG.  1    illustrates that a length L 1  of the example mattress  22  is greater than a length L 2  of the example support box  40 . In the first example bed system  20 , the example base system  24  is conventional and the example mattress  22  is elongated with respect to conventional to allow the use of a conventional base system  24 .  FIG.  3    illustrates that the example secondary frame assembly  44  is sized and dimensioned such that the example primary longitudinal frame rails  50  and primary lateral frame rails  52  are at a primary vertical height H1 and the example secondary longitudinal frame rails  60  and secondary lateral frame rails  62  are at a secondary vertical height H2. The secondary vertical height H2 is above the primary vertical height H1, and a difference D between the primary vertical height H1 and the secondary vertical height H2 is approximately the same as a vertical thickness of the example support box  40 . The example base system  24  is thus configured such that entry of air into the opening  32  at the bottom surface  36  of the mattress  22  is substantially unobstructed. 
     An opening created in the example mattress  22  (or an auxiliary mattress/base combined with a conventional mattress) will allow the user to sleep on their stomach with their face down, creating proper neutral positioning for head, neck, and surrounding structures. The example bed system  20  will help not only people who have neck injuries who want to stomach sleep, but also those who stomach sleep as a habit. For unencumbered breathing, the mattress opening  32  communicates with a fresh air space  70  below the example mattress  22 . The fresh air space may be formed by lengthening the mattress  22  relative to the example support box  40  as shown in  FIG.  1   , by forming a corresponding opening in the support box  40  below the mattress  22 , or by providing a base box capable of dropping away as described in further detail below. 
     Referring now to  FIG.  5    of the drawing, depicted therein is a second example bed system  120  of the present inventio. The second example bed system  120  comprises a mattress  122  and a base system  124 . 
     The example mattress  122  defines a sleeping surface  130 , an opening  132 , a perimeter surface  134 , and a bottom surface  136 . The example opening  132  extends from the sleeping surface  130  to the bottom surface  136 . In all other respects, the structure of the example mattress  122  is or may be conventional (e.g., case and filler material) and will not be described in further detail. 
     The example base system  124  comprises a support box  140 , a primary frame assembly  142 , and a secondary frame assembly  144 . The example primary frame assembly  142  is or may be the same as the example primary frame assembly  42  described above and will not be described again in detail. The example secondary frame assembly  144  comprises at least two secondary rail members  150  and one or more connecting assemblies  152 . Each of the secondary rail members  150  comprises a connecting portion  154 , an extension portion  156 , and a support portion  158 . Only one of the example secondary rail members  150  is visible in  FIG.  5   . At least one secondary lateral frame rail (not visible in  FIG.  5   ) like the secondary lateral frame rails  62  described above may be arranged to extend between the support portions  158  of the secondary rail members  150 . 
     The example connecting assemblies  152  are nuts and bolts arranged to rigidly connect the connecting portions  154  to the primary frame assembly  142 . The example extension portions  156  extend from the connecting portions  154  such that the example support portions  158  are supported at the secondary vertical height H2. The support portions  158  and the lateral frame rail(s) (not visible) support a portion of the example mattress  122  such that a bottom of the opening  132  is unobstructed. The second example bed system  120  may be used in substantially the same manner as the other example bed systems described herein. 
     Referring now to  FIG.  6    of the drawing, depicted therein is a third example bed system  160  of the present invention. The second example bed system  160  comprises a mattress  162  and a base system  164 . 
     The example mattress  162  defines a sleeping surface  170 , an opening  172 , a perimeter surface  174 , and a bottom surface  176 . The example opening  172  extends from the sleeping surface  170  to the bottom surface  176 . In all other respects, the structure of the example mattress  162  is or may be conventional (e.g., case and filler material) and will not be described in further detail. 
     The example base system  164  comprises a support box  180 , a primary frame assembly  182 , and a secondary frame assembly  184 . The example primary frame assembly  182  is or may be the same as the example primary frame assembly  42  described above and will not be described again in detail. The example secondary frame assembly  184  comprises at least two secondary rail members  190  and one or more connecting assemblies like the connecting assemblies  152  described above. Each of the secondary rail members  190  comprises a connecting portion  192 , an extension portion  194 , a support portion  196 , and a leg portion  198 . Only one of the example secondary rail members  190  is visible in  FIG.  6   . At least one secondary lateral frame rail (not visible in  FIG.  6   ) like the secondary lateral frame rails  62  described above may be arranged to extend between the support portions  198  of the secondary rail members  190 . 
     The example connecting assemblies secure the connecting portions  192  to the primary frame assembly  182 . The example extension portions  194  extend from the connecting portions  192  such that the example support portions  196  are supported at the secondary vertical height H2. The leg portion(s)  198  are sized and dimensioned to provide additional support to the support portions  196 . The support portions  196  and the lateral frame rail(s) (not visible) support a portion of the example mattress  162  such that a bottom of the opening  172  is unobstructed. The third example bed system  160  may be used in substantially the same manner as the other example bed systems described herein. 
     Referring now to  FIGS.  7  and  8    of the drawing, depicted at  220  therein is a fourth example bed system  220  constructed in accordance with, and embodying, the principles of the present invention. The fourth example bed system  220  comprises a mattress  222  and a base system  224 . 
     The example mattress  222  defines a sleeping surface  230 , an opening  232 , a perimeter surface  234 , and a bottom surface  236 . The example opening  232  extends from the sleeping surface  230  to the bottom surface  236 . In all other respects, the structure of the example mattress  222  is or may be conventional (e.g., case and filler material) and will not be described in further detail. 
     The example base system  224  comprises a support box  240 , a primary frame assembly  242 , and a secondary frame assembly  244 . The example primary frame assembly  242  and example secondary frame assembly  244  may be constructed in substantially the same manner as the example primary frame assembly  42  and example secondary frame assembly  44  described above and thus will not be described herein again in detail. 
       FIGS.  7  and  8    illustrate that a length L 1  of the example mattress  222  is greater than a length L 2  of the example support box  240 . However, in the fourth example bed system  220 , the example base system  224  is shortened with respect to conventional to allow the mattress  222  to be of conventional size (e.g., length and/or width). The fourth example bed system  220  is otherwise constructed and may be used in substantially the same manner as the other example bed systems described herein. 
     Referring now to  FIG.  9    of the drawing, depicted at  260  therein is a fifth example bed system  260  constructed in accordance with, and embodying, the principles of the present invention. The fifth example bed system  260  comprises a mattress  262  and a base system  264 . 
     The example mattress  262  defines a sleeping surface  270 , an opening  272 , a perimeter surface  274 , and a bottom surface  276 . The example opening  272  extends from the sleeping surface  270  to the bottom surface  276 . In all other respects, the structure of the example mattress  262  is or may be conventional (e.g., case and filler material) and will not be described in further detail. 
     The example base system  264  comprises a support box  280 , a primary frame assembly  282 , and a secondary frame assembly  284 . The example primary frame assembly  282  and example secondary frame assembly  284  may be constructed in substantially the same manner as the example primary frame assembly  242  and example secondary frame assembly  244  of the the fourth example bed system  220  described above and thus will not be described herein again in detail. The example support box  280  is, however, substantially the same length as the example mattress  262 . 
       FIG.  9    illustrates that the example base system  264  is modified to allow the example support box  280  to be bent or otherwise modified or deformed to create a space  290  between bottom surface  276  of the mattress  262  and the support box  280 . In particular, a portion  292  of the example support box  280  is unsupported by either the primary frame assembly  282  or the secondary frame assembly  284  such that the unsupported portion  292  is below the mattress  262  to define the space  290 . The space  290  allows the air flow between the mattress  262  and the support box  280  such that air is not prevented from reaching the opening  272 . The fifth example bed system  260  is otherwise constructed and may be used in substantially the same manner as the other example bed systems described herein. 
       FIG.  10    illustrates a second example mattress  320  that may be used as part of any of the example bed systems  20 ,  120 ,  160 ,  220 , or  260  described herein. The second example mattress  320  as constructed is larger (e.g., queen or king) than the first example mattresses  22 ,  122 ,  162 ,  222 , and  262  (e.g., single, double, full). Accordingly, the example mattress  320  defines a sleeping surface  330 , first and second openings  332   a  and  332   b , a perimeter surface  334 , and a bottom surface (not visible in  FIG.  10   ). Like the openings  32 ,  132 ,  172 ,  232 , and  272  described above, the first and second openings  332   a  and  332   b  both extend from sleeping surface  330  to the bottom surface of the mattress  320 . Any of the base systems  24 ,  124 ,  164 ,  224 , or  264  described above, when properly sized, can be used to support the second example mattress  320 . The second example mattress  320  is otherwise constructed and may be used in substantially the same manner as the other example mattresses described herein. 
     Turning now to  FIGS.  11  and  12    of the drawing, depicted therein is a sixth example bed system  360  constructed in accordance with, and embodying, the principles of the present invention. The sixth example bed system  360  comprises a primary mattress  362   a , a secondary mattress  362   b , and a base system  364 . The example primary mattress  362   a  is or may be conventional and will not be described herein in detail. The example secondary mattress  362   b  defines a sleeping surface  370 , an opening  372 , a perimeter surface  374 , and a bottom surface  376 . The example base system  364  defines a support box  380 , a primary frame assembly  382 , and a secondary frame assembly  384 . The example base box  380  and the primary frame assembly  382  are or may be conventional and will not be described herein in detail. 
     The example secondary frame assembly  384  is or may be constructed in the same manner as the example secondary frame assemblies  44 ,  144 ,  184 ,  244 , or  284  described herein. However, instead of two frame assemblies each supporting a portion of a single mattress, the example primary frame assembly  382  supports the support box  380  and the primary mattress  362   a  and the example secondary frame assembly  384  is adapted to support only the secondary mattress  362   b.    
     The sixth example bed system  360  may thus be formed by adding the secondary mattress  362   b  and secondary frame assembly  384  to a conventional mattress such as the primary mattress  362   a  supported by a conventional support box  380  and conventional primary frame assembly  382 . The sixth example may thus be used without the secondary mattress  362   b  as a conventional bed as shown in  FIG.  11    or with the secondary mattress  362   b  combined with a conventional bed to facilitate face down sleeping as shown in  FIG.  12   . The sixth example bed system  360  is otherwise constructed and may be used in substantially the same manner as the other example bed systems described herein. 
     Turning now to  FIG.  13    of the drawing, depicted therein is a seventh example bed system  420  constructed in accordance with, and embodying, the principles of the present invention. Like the sixth example bed system  360 , the seventh example bed system  420  comprises a primary mattress  422   a , a secondary mattress  422   b , and a base system  424 , but the seventh example bed system  420  further comprises an attachment system  426 . The example primary mattress  422   a  is or may be conventional and will not be described herein in detail. The example secondary mattress  422   b  defines a sleeping surface  430 , an opening  432 , a perimeter surface  434 , and a bottom surface  436 . 
     The example base system  424  comprises a support box  440 , a primary frame assembly  442 , and a secondary frame assembly  444 . The example attachment system  426  is arranged to secure the secondary frame assembly  444  to the primary frame assembly  442  and comprises first and second connecting assemblies  450  and  452 . The example connecting assemblies  450  and  452  are depicted as straps, but bolts, screws, or other connecting systems may be used to form the connecting assemblies  450  and  452  and/or the attachment system  426 . The seventh example bed system  420  is otherwise constructed and may be used in substantially the same manner as the other example bed systems described herein. 
     Turning now to  FIG.  14    of the drawing, depicted therein is an eighth example bed system  460  constructed in accordance with, and embodying, the principles of the present invention. Like the sixth example bed system  360 , the seventh example bed system  460  comprises a primary mattress  462   a , a secondary mattress  462   b , and a base system  464 , but the eighth example bed system  460  further comprises a wheel system  466 . The example primary mattress  462   a  is or may be conventional and will not be described herein in detail. The example secondary mattress  462   b  defines a sleeping surface  470 , an opening  472 , a perimeter surface  474 , and a bottom surface  476 . 
     The example base system  464  comprises a support box  480 , a primary frame assembly  482 , and a secondary frame assembly  484 . The example attachment system  466  is arranged to secure the secondary frame assembly  484  to the primary frame assembly  482  and comprises first and second wheel assemblies  490 . The example wheel assemblies  490  are secured to legs of the secondary frame assembly  484  to facilitate movement of the secondary frame assembly  484  and the secondary mattress  462   b  supported thereby. An attachment system like the example attachment system  426  described above may additionally be used to inhibit inadvertent movement of the secondary mattress  362   b  relative to the primary mattress  362   a . The eighth example bed system  460  is otherwise constructed and may be used in substantially the same manner as the other example bed systems described herein. 
     Turning now to  FIG.  15    of the drawing, depicted therein is a ninth example bed system  520  constructed in accordance with, and embodying, the principles of the present invention. Like the sixth example bed system  360 , the ninth example bed system  520  comprises a primary mattress  522   a , a secondary mattress  522   b , and a base system  524 , but the base system  524  of the ninth example bed system  520  further comprises a height adjustment system  526 . The example primary mattress  522   a  is or may be conventional and will not be described herein in detail. The example secondary mattress  522   b  defines a sleeping surface  530 , an opening  532 , a perimeter surface  534 , and a bottom surface  536 . 
     The example base system  524  comprises a support box  540 , a primary frame assembly  542 , and a secondary frame assembly  544 . The example height adjustment system  526  is arranged to adjust an effective height of the secondary frame assembly  544  such that the sleeping surface  530  of the secondary mattress  522   b  is at a desired height level relative to a sleeping surfaced defined by the primary mattress  522   a . In  FIG.  15   , the height level of the sleeping surface  530  of the secondary mattress  522   b  the same as the height level of the sleeping surfaced defined by the primary mattress  522   a . The example height adjustment system  526  takes the form of adjustable leg assemblies  550  of the secondary frame assembly  544 . In particular, each leg assembly  550  comprises a fixed leg portion  552 , a movable leg portion  554 , and a lock member  556 . The lock member  556  takes the form of a pin that extends through aligned openings  558  formed in the fixed and movable leg portions  552  and  554 , but other height adjustment systems may be used in place of the example pins  556  and holes  558 . The ninth example bed system  520  is otherwise constructed and may be used in substantially the same manner as the other example bed systems described herein. 
     Turning now to  FIG.  16    of the drawing, depicted therein is a tenth example bed system  560  constructed in accordance with, and embodying, the principles of the present invention. Like the sixth example bed system  360 , the seventh example bed system  560  comprises a primary mattress  562   a , a secondary mattress  562   b , and a base system  564 , but the base system  564  of the tenth example bed system  560  further comprises a shelf system  566 . The example primary mattress  562   a  is or may be conventional and will not be described herein in detail. The example secondary mattress  562   b  defines a sleeping surface  570 , an opening  572 , a perimeter surface  574 , and a bottom surface  576 . 
     The example base system  564  comprises a support box  580 , a primary frame assembly  582 , and a secondary frame assembly  584 . The example shelf system  566  is arranged to define a shelf surface  590  below the opening  572 . The example shelf system  566  takes the form of a generally planar member  592  supported by two or more legs  594  of the secondary frame assembly  584 . The tenth example bed system  560  is otherwise constructed and may be used in substantially the same manner as the other example bed systems described herein. 
     An eleventh example bed system  620  constructed in accordance with, and embodying, the principles of the present invention is depicted in  FIGS.  17  and  18   . Like the sixth example bed system  360 , the seventh example bed system  620  comprises a primary mattress  622   a , a secondary mattress  622   b , and a base system  624 , but the base system  624  of the eleventh example bed system  620  further comprises a brace system  626 . The example primary mattress  622   a  is or may be conventional and will not be described herein in detail. The example secondary mattress  622   b  defines a sleeping surface  630 , an opening  632 , a perimeter surface  634 , and a bottom surface  636 . 
     The example base system  624  comprises a support box  640 , a primary frame assembly  642 , and a secondary frame assembly  644 . The example brace system  626  comprises at least one or more lateral brace members  650  ( FIG.  17   ) and one or more end brace members  652  ( FIG.  18   ). The brace members  650  and/or  652  extend between pairs of legs  654  defined by the secondary frame assembly  644 . The example brace system  626  comprises brace members  650  and  652  in the form of X-braces configured to rigidify and stabilize the secondary frame assembly  644 . The eleventh example bed system  620  is otherwise constructed and may be used in substantially the same manner as the other example bed systems described herein. 
       FIG.  19    illustrates a first example mattress system  660  that may be used by any of the sixth through eleventh bed systems described above. The first example mattress system  660  comprises a first example primary mattress  662  and a first example secondary mattress  664 . The first example primary mattress  662  defines a primary sleeping surface  670  and a primary perimeter surface  672 . The first example secondary mattress  664  defines an opening  680 , a secondary sleeping surface  682 , and a secondary perimeter surface  684 . The primary perimeter surface  672  takes the shape of a rectangle with rounded corners in top plan view. The secondary perimeter surface  684  also takes the shape of a rectangle with rounded corners, but the longitudinal axis of the rectangle defined by the secondary perimeter surface  684  is substantially orthogonal to the longitudinal axis of the rectangle defined by the primary perimeter surface  672 . Further, a width dimension WS of the of the secondary perimeter surface  684  in a dimension parallel to the longitudinal axis of the rectangle defined by the secondary perimeter surface  684  is substantially the same as a width dimension WP of the primary perimeter surface orthogonal to the longitudinal axis of the rectangle defined by the primary perimeter surface  672 . 
       FIG.  20    illustrates a second example mattress system  720  that may be used by any of the sixth through eleventh bed systems described above. The second example mattress system  720  comprises a second example primary mattress  722  and a second example secondary mattress  724 . The second example primary mattress  722  defines a primary sleeping surface  730  and a primary perimeter surface  732 . The second example secondary mattress  724  defines first and second openings  740   a  and  740   b , a secondary sleeping surface  742 , and a secondary perimeter surface  744 . The primary perimeter surface  732  takes the shape of a rectangle with rounded corners in top plan view. The secondary perimeter surface  744  also takes the shape of a rectangle with rounded corners, but the longitudinal axis of the rectangle defined by the secondary perimeter surface  744  is substantially orthogonal to the longitudinal axis of the rectangle defined by the primary perimeter surface  732 . Further, a width dimension WS of the of the secondary perimeter surface  744  in a dimension parallel to the longitudinal axis of the rectangle defined by the secondary perimeter surface  744  is substantially the same as a width dimension WP of the primary perimeter surface orthogonal to the longitudinal axis of the rectangle defined by the primary perimeter surface  732 . 
       FIG.  21    illustrates a third example mattress system  760  that may be used by any of the sixth through eleventh bed systems described above. The third example mattress system  760  comprises a third example primary mattress  762  and a third example secondary mattress  764 . The third example primary mattress  762  defines a primary sleeping surface  770  and a primary perimeter surface  772 . The third example secondary mattress  764  defines an opening  780 , a secondary sleeping surface  782 , and a secondary perimeter surface  784 . The primary perimeter surface  772  takes the shape of a rectangle with rounded corners in top plan view. The secondary perimeter surface  784  defines a generally rectangular base portion  790  and a rounded extension portion  792  extending from the base portion  790  in a direction opposite the primary mattress  762 . The longitudinal axis of the rectangle defined by the base portion  790  is substantially orthogonal to the longitudinal axis of the rectangle defined by the primary perimeter surface  772 . In the third example mattress system, a width dimension WS of the of the secondary perimeter surface  784  in a dimension parallel to the longitudinal axis of the rectangle defined by the secondary perimeter surface  784  is slightly shorter than a width dimension WP of the primary perimeter surface  772  orthogonal to the longitudinal axis of the rectangle defined by the primary perimeter surface  772 . A width dimension WE of the extension portion  792  is smaller than the width dimension WS. 
       FIG.  22    illustrates a fourth example mattress system  820  that may be used by any of the sixth through eleventh bed systems described above. The fourth example mattress system  820  comprises a fourth example primary mattress  822  and a fourth example secondary mattress  824 . The fourth example primary mattress  822  defines a primary sleeping surface  830  and a primary perimeter surface  832 . The fourth example secondary mattress  824  defines first and second openings  840   a  and  840   b , a secondary sleeping surface  842 , and a secondary perimeter surface  844 . The primary perimeter surface  832  takes the shape of a rectangle with rounded corners in top plan view. The secondary perimeter surface  844  defines a generally rectangular base portion  850  and an extension portion  852  with rounded corners extending from the base portion  850  in a direction opposite the primary mattress  822 . The longitudinal axis of the rectangle defined by the base portion  850  is substantially orthogonal to the longitudinal axis of the rectangle defined by the primary perimeter surface  832 . In the fourth example mattress system, a width dimension WS of the of the secondary perimeter surface  844  in a dimension parallel to the longitudinal axis of the rectangle defined by the secondary perimeter surface  844  is slightly shorter than a width dimension WP of the primary perimeter surface  832  orthogonal to the longitudinal axis of the rectangle defined by the primary perimeter surface  832 . A width dimension WE of the extension portion  852  is smaller than the width dimension WS. 
       FIG.  23    illustrates a fifth example mattress system  860  that may be used by any of the sixth through eleventh bed systems described above. The fifth example mattress system  860  comprises a fifth example primary mattress  862  and a fifth example secondary mattress  864 . The fifth example primary mattress  862  defines a primary sleeping surface  870  and a primary perimeter surface  872 . The fifth example secondary mattress  864  defines an opening  880 , a secondary sleeping surface  882 , and a secondary perimeter surface  884 . The primary perimeter surface  872  takes the shape of a rectangle with rounded corners in top plan view. The secondary perimeter surface  884  defines a generally rectangular base portion  890  and a rounded extension portion  892  extending from the base portion  890  in a direction opposite the primary mattress  862 . The longitudinal axis of the rectangle defined by the base portion  890  is substantially orthogonal to the longitudinal axis of the rectangle defined by the primary perimeter surface  872 . In the fifth example mattress system, a width dimension WS of the of the secondary perimeter surface  884  in a dimension parallel to the longitudinal axis of the rectangle defined by the secondary perimeter surface  884  is slightly shorter than a width dimension WP of the primary perimeter surface orthogonal to the longitudinal axis of the rectangle defined by the primary perimeter surface  872 . A width dimension WE of the extension portion  892  is substantially the same as the width dimension WS. 
       FIG.  24    illustrates a sixth example mattress system  920  that may be used by any of the sixth through eleventh bed systems described above. The sixth example mattress system  920  comprises a sixth example primary mattress  922  and a sixth example secondary mattress  924 . The sixth example primary mattress  922  defines a primary sleeping surface  930  and a primary perimeter surface  932 . The sixth example secondary mattress  924  defines first and second openings  940   a  and  940   b , a secondary sleeping surface  942 , and a secondary perimeter surface  944 . The primary perimeter surface  944  takes the shape of a rectangle with rounded corners in top plan view. The secondary perimeter surface  944  defines a generally rectangular base portion  950  and an extension portion  952  with rounded corners extending from the base portion  950  in a direction opposite the primary mattress  922 . The longitudinal axis of the rectangle defined by the base portion  950  is substantially orthogonal to the longitudinal axis of the rectangle defined by the primary perimeter surface  932 . In the sixth example mattress system, a width dimension WS of the of the secondary perimeter surface  944  in a dimension parallel to the longitudinal axis of the rectangle defined by the secondary perimeter surface  944  is slightly shorter than a width dimension WP of the primary perimeter surface  932  orthogonal to the longitudinal axis of the rectangle defined by the primary perimeter surface  932 . A width dimension WE of the extension portion  952  is substantially the same as the width dimension WS. 
       FIGS.  25  and  26    illustrate a cover member  960  that may be used by a mattress such as the mattress  22  of the first example bed system  20  described above. The cover member  960  comprises a main portion  962 , an opening portion  964 , and a perimeter portion  966 . The main portion  962  is adapted to cover the sleeping surface  30  of the mattress of the first example bed system  20 . The opening portion  964  is sized, dimensioned, and arranged in the main portion  962  to extend into the opening  32  of the first example mattress  22 . The perimeter portion  966  is configured to extend along at least a portion of the perimeter surface  34  of the mattress  22 . The cover system  960  may be a bed sheet made of conventional bed sheet materials or a mattress cover made of conventional mattress cover materials. In addition, two of the cover members  960  may be used: a first as a mattress cover, and a second as a sheet between the mattress cover and the user of the mattress  22 . Finally, the cover member  960  may be “flat” or “fitted”. A fitted cover member  960  may further comprise elastic or other resiliently deformable material arranged to extend at least partly along the bottom surface  36  defined by the first example bed system  20  to secure the cover member  960  in place relative to the mattress. 
       FIGS.  27  and  28    illustrate an example cover system  970  comprising a primary cover member  972  and a secondary cover member  974 . The example cover system  970  may be used by the mattresses  362   a  and  362   b  of the sixth example bed system  360  described above. The primary cover member  972  is or may be conventional and comprises a primary main portion  980  and a primary perimeter portion  982 . The secondary cover member  974  comprises a secondary main portion  990 , an opening portion  992 , and a secondary perimeter portion  994 . The secondary cover member adapted to cover the sleeping surface  370  of the secondary mattress  362   b  of the sixth example bed system  360 . The opening portion  992  is sized, dimensioned, and arranged in the secondary main portion  990  to extend into the opening  372  of the secondary mattress  362   b  of the sixth example bed system  360 . The perimeter portion  994  is configured to extend along at least a portion of the perimeter surface  374  of the secondary mattress  362   b . The cover members  972  and  974  may be bed sheets made of conventional bed sheet materials or mattress covers made of conventional mattress cover materials. In addition, two of the cover members  972  and  974  may be used on each mattress: a first as a mattress cover, and a second as a sheet between the mattress cover and the user. Finally, the cover members  972  and  974  may be “flat” or “fitted”. A fitted cover member  972  and/or  974  may further comprise elastic or other resiliently deformable material arranged to extend at least partly along the bottom surface (e.g., bottom surface  376  of the secondary mattress  362   b ) to secure the cover member  974  in place relative to the mattress. 
     Cover members such as the cover members  960  and  974  may be configured to cover any of the mattresses defining an opening as described herein.