Patent Publication Number: US-2015082549-A1

Title: Bedding systems

Description:
FIELD OF THE INVENTION 
     The present invention relates to bedding systems and in particular to mattresses. 
     BACKGROUND TO THE INVENTION 
     A number of mattresses presently exist on the market. The applicants wish to provide an improved mattress for sleeping and possibly therapeutic purposes. 
     It is against this background and the problems and difficulties associated therewith that the present invention has been developed. 
     SUMMARY OF THE INVENTION 
     According to a first aspect of preferred embodiments herein described there is provided a mattress for a bed, the mattress comprising: an upper layer formed from visco elastic foam material of a first kind; an intermediate layer formed from visco elastic foam material of a second kind; a lower layer formed from foam material of another kind; wherein the intermediate layer is provided between the upper layer and the lower layer; the upper layer and the intermediate layer have a combined thickness of at least 50 mm; and the lower layer has a thickness of at least 70 mm. 
     The upper layer, intermediate layer and the lower layer may each consist of a single unitary layer. 
     Preferably the upper layer and intermediate layer each consist of single unitary layer and the lower layer consists of two layers, namely an upper-lower layer and a lower-lower layer. 
     Preferably the layers are glued together with the upper layer being at least 25 mm in thickness, the intermediate layer being at least 30 mm in thickness and the lower layer being at least 100 mm in thickness. 
     Preferably the upper layer is formed from visco elastic foam of a hardness between 30 and 60 N; the intermediate layer is formed from visco elastic foam of a hardness between 70 and 110 N; and the lower layer is formed from foam of a hardness between 85 and 130 N. 
     Preferably the mattress includes a plurality of boundary members extending along the lateral sides of the mattress to provide the mattress with relatively firm side support portions. 
     Preferably the mattress includes a plurality of boundary members extending along the ends of the mattress to provide the mattress with relatively firm end support portions. 
     Preferably the upper layer is of a larger planar size than the intermediate layer and the lower layer, the boundary members surrounding the periphery of the intermediate layer and the lower layer, with the upper layer being disposed above the intermediate layer, the lower layer and the boundary members. 
     Preferably the density of the upper layer of visco elastic foam material is between 47 and 57 kg/m3; the density of the intermediate layer of visco elastic foam material is between 55 and 65 kg/m3; and the density of the lower layer of foam material is between 31 and 41 kg/m3. 
     Preferably the hardness of the upper layer of visco elastic foam material is between 30 and 60 (IFD 40%); the hardness of the intermediate layer of visco elastic foam material is between 75 and 105 (IFD 40%); and the hardness of the lower layer of foam material is between 115 and 155 (IFD 40%). 
     According to a second aspect of preferred embodiments herein described there is provided a mattress for a bed, the mattress comprising: at least one layer of visco elastic foam material; wherein a number of vertically extending ventilation passages extend through the at least one layer of visco elastic material so as to provide the mattress with a number of supportive zones. 
     Preferably the ventilation passages provide the mattress with seven supportive zones 
     Preferably at least some of the zones are of a depth of least 250 mm in the longitudinal direction along the mattress. 
     Preferably at least some of the zones are of a depth of least 300 mm in the longitudinal direction along the mattress. 
     Preferably the ventilation passages provide the sleeping zones with relatively soft and relatively firm sleeping zones that alternate along the length of the mattress. 
     Preferably the relatively firm sleeping zones each include only two or three internal rows of vertically extending passages. 
     Preferably the relatively soft sleeping zones each include less than 10 internal rows of vertically extending passages. 
     Preferably the relatively soft sleeping zones each include less than 6 internal rows of vertically extending passages. 
     According to a third aspect of preferred embodiments herein described there is provided a mattress for a bed, the mattress comprising: an upper layer formed from visco elastic foam material of a first kind; an intermediate layer of foam formed from visco elastic foam material of a second kind; and a lower layer formed from foam material of a third kind; wherein the mattress includes a number of vertically extending ventilation passages extending through the mattress from the upper surface of the upper layer through the lower surface of the lower layer. 
     According to a fourth aspect of preferred embodiments herein described there is provided a mattress for a bed comprising at least one layer of foam material wherein a number of vertically extending ventilation passages extend through the at least one layer of foam material so as to provide the mattress with a number of supportive zones. 
     According to a fifth aspect of preferred embodiments herein described there is provided a method of manufacturing a mattress, including: proactively forming a number of vertically extending ventilation passages in at least a one layer of visco elastic foam material, despite the visco elastic foam material having an open core structure allowing natural ventilation; and using the at least one layer of visco elastic foam material in the construction of the mattress. 
     Preferably proactively forming a number of vertically extending ventilation passages in the at least one layer of visco elastic foam material comprises forming the vertically extending passages in a first layer of visco elastic foam material of a first hardness and second layer of visco elastic foam material of a second hardness. 
     Preferably using the at least one layer of visco elastic foam material comprises fixing the second layer to a third layer of foam material in a manner in which the second layer provides an intermediate layer between the first layer of visco elastic foam material and the third layer of foam material. 
     Preferably applying the at least one layers of visco elastic foam material comprises fixing the first layer of visco elastic foam material to the second layer of visco elastic foam material. 
     Preferably the first layers of visco elastic foam material is larger than the second and third layers such that boundary members can be positioned around the periphery of the second and third foam layers to support the periphery of the first layer of foam material from below. 
     According to a sixth aspect of preferred embodiments herein described there is provided a method of manufacturing a mattress comprising: providing number of layers of visco elastic foam material; and forming a mattress using the layers of visco elastic foam material wherein a number of ventilation passages are provided that extend all the way through the mattress. 
     Preferably the method includes providing a first layer formed from visco elastic foam material of a first kind, gluing thereto a second and third layer of visco elastic material of a second and third kind to form a layered structure. 
     Preferably gluing thereto includes gluing a first pair of end supportive portions to the first, second and third layers at a respective upper end and a respective lower end of the layers. 
     Preferably the outward surface of third layer in the layered structure is then glued to a fourth layer of visco elastic material and a second pair of end supportive portions are glued to the first pair of end support portions to provide end supports extending from beneath the first layer. 
     Preferably the method includes gluing lateral side support portions that extend from beneath the first layer. 
     Preferably the ventilation passages extend through the first, second, third and fourth layers and the support portions do not include any ventilation passages. 
     Hardness measurements are to be understood as referring to compressing a standard sized piece of foam to 40% with the force required to achieve that compression being measured in Newtons. Hardness tests are those applied to standard Dunlop foams. For example Dunlop Enduro™ EN36-130 foam has a hardness range of 120-150. Density refers to the weight of the foam in kilograms per cubic meter. For example Dunlop Enduro™ EN36-130 foam has a density of about 36 kg/m3. Resilience and indentation factors are also standard measures. For example Dunlop Enduro™ EN36-130 has an indentation factor of about 2.39 and a resilience of about 55%. Dunlop foam technical manuals and standards are readily available. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       In order to facilitate a better understanding of the present invention, several preferred embodiments will now be described with reference to the accompanying drawings, in which: 
         FIG. 1  provides a perspective view of a mattress according to a first preferred embodiment of the present invention; 
         FIG. 2  provides a plan view of the mattress shown in  FIG. 1 ; 
         FIG. 3  provides an exploded perspective view of the mattress shown in  FIG. 1 ; 
         FIG. 4  provides a detailed plan view of the mattress shown in  FIG. 1 ; 
         FIGS. 5   a  and  5   b  illustrate a method according to a second preferred embodiment of the present invention; 
         FIGS. 6 and 7  provide spacing views illustrating rows of apertures in mattresses according to further preferred embodiments of the present invention; 
         FIGS. 8 to 10  illustrate further preferred embodiments; and 
         FIGS. 11 to 20  provide several views illustrating yet further preferred embodiments of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     It is to be appreciated that each of the embodiments is specifically described and that the present invention is not to be construed as being limited to any specific feature or element of any one of the embodiments. Neither is the present invention to be construed as being limited to any feature of a number of the embodiments or variations described in relation to the embodiments. 
     Referring to  FIGS. 1 to 3  there is shown a mattress  10  according to a first preferred embodiment of the present invention. The mattress  10  includes an upper layer  12 , an intermediate layer  14  and a lower layer  16 . The mattress  10  is considered to be of advantageous form as well to provide a number of advantageous supportive zones  18 . This is described in further detail below. 
     The upper layer  12  is formed from visco elastic foam material of a first density &amp; hardness and provides a unitary visco elastic foam top layer. The intermediate layer  14  is formed from visco elastic foam material of a second density &amp; hardness and provides a unitary visco elastic foam middle layer. The lower layer  16  comprises a supportive standard foam layer formed from foam material of a third density &amp; hardness. In the embodiment the layers are glued together with a non-toxic water based adhesive to form the advantageous mattress  10 . 
     More particularly, the upper layer  12  comprises visco elastic foam material for providing relative slow recovery support to the neck, shoulders, knees and back of the user. The intermediate layer  14  comprises visco elastic foam for providing relatively slow recovery support. 
     The upper layer  12  has a hardness of about 40N. The intermediate layer  14 , on the other hand, has a hardness of about 90N. This provides a factor about 2 times the hardness of the upper layer  12 . Of course various embodiments are possible including embodiment where the factor is greater than 2 times. 
     The lower layer  16  comprises a resilient standard foam designed to support the upper layer  12  and the intermediate layer  14 . The lower layer  16  assists in distributing pressure while providing a suitable mattress core. The lower layer  16  has a hardness of about 130 N. 
     Advantageously the mattress  10  provides a triple layer comprising three (3) distinct layers and grades of foam. 
     The applicant considers that in the industry a single layer of visco elastic foam is typically used to provide a mattress. It may be also that occasionally, the visco elastic foam is provided together with a standard foam base. The present embodiment is considered to provide a substantial improvement to existing visco elastic foam beds in terms of the support provided to the head, neck, shoulders, hips, body and limbs of the user. 
     In the present embodiment the lower layer  16  comprises a premium grade standard foam base. As described there is provided a relatively firm premium visco elastic foam intermediate layer  14  above the lower layer  16 . A softer further premium visco elastic foam upper layer  12  is provided above the intermediate layer  14 . 
     In the advantageous combination, the lower layer  16  provides a good firm supportive base for the intermediate layer  14  and the upper layer  12 . The lower layer  16  affords sufficient “give” to allow a relatively high degree of comfort. 
     In the embodiment, the lower layer  16  is not a visco elastic “memory foam” layer but comprises a premium grade open cell foam. The open cell foam does not include any CFCs or any other toxins. 
     By virtue of the intermediate layer  14  being formed from relatively firm premium visco elastic foam (“memory foam”) this is considered to advantageously even out and distribute pressure from the heavier/bulkier parts of the body, such as the shoulders and hips, and advantageously promotes improved spinal posture. 
     The upper layer  12  provides an added comfort layer advantageously configured to provide a softer supportive layer catering, in particular, for the user&#39;s limbs and face. 
     In the present embodiment it has been found that Dunlop Viscoflex™ VF52-40 and VF60-90 provide a particularly advantageous combination for the upper layer  12  and the intermediate layer  14 . A Dunlop Enduro™ EN36-130 foam has been found to be advantageous for the lower layer  16 . Associated characteristics of the layers of foam tabulated below. 
     
       
         
           
               
               
               
               
               
               
             
               
                   
                   
               
               
                   
                   
                 Density 
                 Hardness 
                 Indentation 
                 Resilience 
               
               
                   
                 Grade 
                 (kg/m3) 
                 (IFD 40%) 
                 Factor 
                 MIN % 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
            
               
                   
                 VF52-40 
                 52 
                 35-55 
                 2.67 
                 5 
               
               
                   
                 VF60-90 
                 60 
                  80-100 
                 2.19 
                 15 
               
               
                   
                 EN36-100 
                 36 
                  95-120 
                 2.44 
                 55 
               
               
                   
                 EN36-130 
                 36 
                 120-150 
                 2.39 
                 55 
               
               
                   
                   
               
               
                   
                 *Source Dunlop Catalogue June 2007 
               
            
           
         
       
     
     In the embodiment the upper layer  12  has a thickness of about 35 mm, the intermediate layer  14  has a thickness of about 50 mm and the lower layer has a thickness of about 130 mm. Such thicknesses have been seen to advantageously provide sleeping comfort and, in the applicant&#39;s opinion, a degree of therapeutic comfort as well. Different thicknesses of the layers are of course possible. 
     In preferred embodiments upper layer and intermediate layer combined thicknesses are preferably at least 60 mm and the lower layer thickness is at least 80 mm. Other ranges are of course possible. In addition, the provision of the layered sandwich structure is considered to be particularly advantageous in combination with the seven distinct supportive zones  18 . 
     As shown in  FIG. 2  the zones  18  start from a first end  20  of the mattress  10  and are spaced therealong. The zones  18  terminate at an opposite end  22 . A first zone  24  is provided at the first end  20  of the mattress  10  and comprises a relatively firm zone  26 . A second zone  28  is provided adjacent the first zone  24  and comprises a relatively soft zone  30 . A third zone  32  adjacent the second zone  28  comprises another relatively firm zone  26 . 
     A fourth zone  34  adjacent the third zone  32  provides a central relatively soft zone. The zones described alternate along the full length of the mattress  10 . The fourth zone  34  provides a mirror axis  36 . As a result a fifth zone  38 , a sixth zone  40  and a seventh zone  42  are also provided. 
     In order to provide the zones  18 , a plurality of relatively small apertures  44  are provided. The apertures  44  extend through the upper layer  12 , the intermediate layer  14  and the lower layer  16  to provide a plurality of ventilation passages  46 . As shown in  FIG. 3 , the ventilation passages  46  extend all the way through the mattress  10  from the upper surface  48  of the upper layer  12  to the lower surface  50 , of the lower layer  16 . 
     The ventilation passages  46  are advantageously spaced in rows  52 . As shown the rows  52  are spaced apart along the length of the mattress  10 . The ventilation passages  46  in each row extend across the mattress  10 . 
     The ventilation passages  46  are advantageously sized to be about 5 mm in diameter which serves to retain a consistency of the foam support as well as provide advantageous breathability. The ventilation passages  46  are spaced about 15 mm apart in reach row. 
     The supportive zones  18  are provided using a longitudinal spacing of about 70 mm between adjacent rows in the relatively firm zones  30  and a spacing of about 50 mm in the relative soft zones  26 . The size of each relatively soft zone  30  is advantageously about 1.5 times the size of each relatively firm zone  26 . This has been seen to advantageously provide comfort to the end user in the 3 layer mattress  10  as described. 
     As a combination, the mattress  10  is considered to form an advantageous “sandwich” of various open cell foams. The open cell foams advantageously provide breathability due to their open cell structure already known as being ‘fully ventilated’. The applicant has further provided additional ventilation passages  46  as described. The applicant further considers that, to the best of the applicant&#39;s knowledge, this goes against conventional judgement and provides a significant improvement to existing visco elastic mattresses. The applicant considers that, to the best of the applicant&#39;s knowledge, such mattresses have never been ventilated in such a manner in the past and that this provides significant advantages. 
     More particularly the ventilation passages  46  are provided by punching out (in a predetermined ratio) the series of 5 mm diameter cores. The addition of the apertures  44  provides the advantageous zoning structure in addition to the open cell structure of the foam. To the best of the applicant&#39;s knowledge, the applicant is not aware of any mattresses having punched out cores to provide several comfort zones along the length of the mattress. 
     In the embodiment the spacing of the ventilation passages  46  is carefully selected to ensure than pressures above 45 mmHg are not provided even in the case of a 100 kg male in a normal sleeping position that is: (i) when lying on his back; or (ii) when lying on his side. 
     In such a case the seven zoned 3 layered visco elastic structure is considered to advantageously serve to reduce pressure on the hips and shoulders and provide a comfortable and therapeutic sleeping position. Pressures less than 45 mmHg are advantageously provided for this purpose. In comparison to standard foam mattresses, the mattress  10  is considered to reduce pressure relatively significantly on all body parts. 
     As discussed, the ventilation passages  46  in the zoned structure are considered to provide advantageous ventilation to assist with ensuring comfortable sleeping. This ventilation provides a notably comfortable sleeping experience in terms of current known issues. With the present embodiment the ventilation passages  46  serve to limit adverse heat build up as well as to provide the advantageous supportive zones  18 . By varying the distance between rows of the ventilation passages  46  softer zones advantageously accommodate the heavier/bulkier parts of the body. This further enhances the various functions of the triple layer foam sandwich. With standard bedding mattresses of foam material may act as a heat trap and may far exceed comfortable sleeping temperatures. 
     Each of the foams described is, in this case, an Australian made breathable visco elastic foam that does not contain formaldehyde or CFCs. Furthermore, the mattress  10  does not contain any metal or metal fittings. The applicant considers that this may be advantageous because there is some evidence that metal beds and spring mattresses amplify electro-magnetic radiation and may cause restless sleep, and some health disorders. As such, in the present embodiment, the advantageous comfort and breathability is provided without the provision of metal springs. In terms of the support provided by the foam material, it is preferred that the foam is not vacuum packed such that the visco foam material maintains a good appearance without any cell wall collapse. 
     In addition to providing comfort while sleeping, the mattress  10  includes four elongate boundary members  54  positioned underneath the upper layer  12  as shown. Each boundary member  54  is arranged to abut the lower surface  56  of the upper layer  12  and extend along the four sides  58  of the mattress  10 . The elongate members  54  are advantageously provided as standard high hardness foam of about 200N. This hardness is greater than 1.4 times the hardness of the lower layer  16 . The applicants have found boundary members made of Dunlop Endure EN38-200 foam advantageously maintain mattress strength and rigidity. The upper layer  12  provides a relatively soft touch at the edge around the boundary members  54 . 
     The upper layer  12  is of a relatively larger planar size than the intermediate layer  14  and the lower layer  16 . The boundary members  54  extend around the periphery  60  of the intermediate layer  14  and the lower layer  16 . The upper layer  12  is disposed above the intermediate layer  14 , the lower layer  16  and the boundary members  54 . 
     As shown in  FIG. 4 , the boundary area  62  adjacent the edge of the mattress  10  from above is advantageously provided with an increased degree of firmness due to support from the relatively firm boundary member  54  with the upper layer  12  being relatively soft to the touch. 
     As would be apparent from the drawings the passages  46  extend though the entire mattress  10  and also define the way the zoning is provided. The elongate members  54  provide a firm edge support arrangement where the members  54  are glued in position. The elongate members  64  are about 5 cm by 5 cm in cross-section. 
     In terms of the upper layer  12 , the distance  64  to the ventilation passages is about 5 cm. In preferred embodiments the distance  64  is between 5 to 20 cm. The longitudinal edge spacing distance  66  is approximately 75 mm. The upper layer  12  covers the firm edge over the top to give an advantageously soft feel. The elongate members  54  (firm edges) are not perforated and neither is the portion of the upper layer  12  above the elongate members  54 . In some embodiments the upper layer  12  is perforated above the elongate members  54 . 
     The following three rows  68  of passages  46  are spaced at 70 mm. This provides a first inner zone depth  70  of about 280 mm less the distance  66 . The following 6 rows are spaced at 50 mm. This provides a second inner zone depth  72  of about 300 mm. Following this the zoning arrangement includes: a third inner zone depth  74  of 280 mm; a fourth inner zone depth  78  of 300 mm; a fifth inner zone depth  80  of 280 mm; a sixth inner zone depth  82  of 300 mm; and a seventh inner zone depth  84  of 280 mm. 
     The zones alternate in a manner wherein relatively firm zones  26  are provided at each end of the mattress  10 . The soft firm zones  30 , are positioned between the relatively soft zones  26 . As a result, at least some of the zones are of a width of least 300 mm in the direction along the mattress  10 . 
     The mattress  10  is symmetrical through the mirror axis  36  midway along the length of the mattress  10 . A longitudinal mirror axis  76  is also provided. The symmetrical nature of the mattress allows the mattress to be rotated with no real change in configuration. 
     In preferred embodiments the depth from the edge of the bed to the second zone is preferably between 95% to 100% of the second zone depth  72 . The second zone depth  72 , the fourth zone depth  78  and the sixth zone depth  82  are preferably equal in size. The third zone depth  74  and the fifth zone depth  78  are preferably between 95% to 100% of the second zone depth  72 . The upper row  77  and the lower row  79  shown in  FIG. 3  are not present in one embodiment. 
     A method  86  according to a further preferred embodiment of the present invention is shown in  FIGS. 5   a  and  5   b . In the method  86  at block  88  an upper layer  90 , of VF52-40 material is ventilated with an advantageous 7 zone sleeping pattern that is similar to the patterns previously described. This is achieved by proactively forming a number of vertically extending ventilation passages through the upper layer  90 . This is despite the upper layer  90  including visco elastic material that has an open core structure allowing ventilation. 
     In the method  86  at block  92  an upper lower layer  94  and lowermost layer  96  are fixed together to form a lower core  98 . 
     As detailed at block  100  the upper lower layer  94  and the lowermost layer  96  are ventilated with an advantageous 7-zone sleeping pattern prior to gluing. The upper lower layer  94  and the lowermost layer  96  are then advantageously glued together using non toxic adhesives. As part of the method  86  this includes aligning the apertures by inserting a number of alignment elements in the form of rods through apertures in both the upper lower layer  94  and lowermost layer  96  during the gluing process. 
     The upper layer  90  and the lower core  98  are then arranged and glued in a similar manner to provide continuous and aligned ventilation passages. The method  86  is accordingly used to provide a 3 layered mattress of substantial thickness. It is to be appreciated that the upper layer is 50 mm on both sides and at the top and foot more than the intermediate and lower layers. In embodiments, at least two layers need to be aligned prior to and for gluing after the holes have been punched. 
     The intermediate layer (upper lower layer) comprises VF60-90 foam of dimensions 1940×1730×50 mm. The lower layer (lowermost layer) comprises EN36-130 foam of dimensions 1940×1730×130 mm. The ventilation is provided with a hole punching system. 
     At block  102  a number of side rails  104  are provided for abutting against the lower surface of the upper layer  98  to provide continuous peripheral support. At block  106  the upper layer  90 , the side rails  104  and the lower core  98  are glued to provide a complete mattress  108 . This provides an advantageous three layer open cell foam mattress with seven zones of comfort as described. 
     Various sizes of mattress are presently preferred including the sizes detailed below. 
     
       
         
           
               
               
               
               
             
               
                   
                   
               
               
                   
                 Size 
                 Length 
                 Width 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
            
               
                   
                 King 
                 2,030 mm 
                 1,830 
                 mm 
               
               
                   
                 Queen 
                 2,030 mm 
                 1,530 
                 mm 
               
               
                   
                 Double 
                 1,870 mm 
                 1,370 
                 mm 
               
               
                   
                 King Size Single 
                 2,030 mm 
                 1,060 
                 mm 
               
               
                   
                 Long Single 
                 2,030 mm 
                 920 
                 mm 
               
               
                   
                 Single 
                 1,870 mm 
                 920 
                 mm 
               
               
                   
                   
               
            
           
         
       
     
     In this case the apertures are 5 mm in diameter. It is presently preferred that apertures are between 2 to 5 mm in diameter. In each horizontal row of cores (i.e. from side to side) the spacing between holes is 15 mm. It is presently preferred that the spacing ranges between say 10 to 30 mm. 
       FIG. 6  illustrates a further preferred embodiment of the present invention. The ratio of spacing between relatively soft zones and relatively firm zones is about 7/5 (1.4). Ratios between 1.2 to 1.7 are presently preferred. 
       FIG. 6  illustrates an embodiment where the first zone depth is precisely 95% of the second zone depth. The first zone depth and the seventh zone depth are equal. The first zone depth and the seventh zone depth are only slightly larger than the third zone depth and the firth zone depth. The third zone depth and the firth zone depth are also equal). The bed is advantageously formed symmetrically about x and y axes. Each of the soft zones has three intermediate rows and each of the hard zones have five intermediate rows. A further preferred embodiment is shown in  FIG. 7 . Again the bed is dominated by a 1.4 relatively firm to soft row spacing (70/50 mm). In the embodiment the first zone depth and the seventh zone depth are reduced in size each having only two intermediate rows. 
     The embodiment described comprises rails on both the sides and top of the bed for further reinforcing the firmness of the peripheral zone. Thus in the embodiment the mattress advantageously comprises 3 separate layers of foam and rails on both sides and on the top and foot. In yet further designs rails are provided only on both sides or only on the top and foot of the beds. Yet further embodiments do not includes rails at all. Of course several variations are possible. Preferably the rails are not punched in order to advantageous provide a relatively rigid peripheral zone. 
       FIG. 8  illustrates a seven zoned mattress  110  according to a further embodiment of the present invention. The mattress  110  includes an upper layer  112  formed from visco elastic foam material of a first kind, an intermediate layer  114  formed from visco elastic foam material of a second kind and a lower layer  116  formed from visco elastic foam material of another kind. 
     The upper layer  112  and the intermediate layer  114  are formed from foam material to provide single unitary layers (without any sub-layers). The lower layer  116  is provided as a layered structure  117  comprising an upper-lower layer  118  and a lower-lower layer  120 . In the embodiment shown in  FIG. 8 , the upper lower layer  118  and the lower-lower layer  120  are formed from visco elastic foam material of the same kind 
       FIG. 9  illustrates a further embodiment in the form of a mattress  122 . In the mattress  122  an upper-lower layer  124  and a lower-lower layer  126  are formed from foam material, each of a different kind. The upper-lower layer  124  is formed from EN-36-100 having a density of about 36 kg/m3 and a hardness of about 90-120 IFD 40%. The lower-lower layer  126  is formed from EN-36-30 having a density of about 36 kg/m3 and a hardness of about 120-150 IFD 40%. 
     The manufacture and form of the mattress  110  and the mattress  120  are similar, apart from the difference in the lower layer. 
     As shown in the embodiment of  FIG. 8 , the upper layer  112 , the intermediate layer  114 , the upper-lower layer  118  and the lower-lower layer  120  are provided as layers of visco elastic foam material. A number of end rails  128  are also provided. In the mattress  110  a number of ventilation passages  130  extend all the way through the mattress  110 . 
     At block  132  the upper layer  112  is glued to the intermediate layer  114  and the upper lower layer  118  to form a layered structure  134 . A first pair of end supportive portions  136  are also glued in the gluing step at a respective upper end  138  and a respective lower end  140  of the layered structure  134 , underneath the upper layer  112 . 
     At block  142 , the layered structure  134  and the lower-lower layer  120  are separately ventilated. The holes are aligned using dowels that are positioned to extend through corresponding holes such that the ventilation passages  130  will extend through the full thickness of the mattress  110  in a relatively uninterrupted manner. 
     The outward surface  144  of the upper-lower layer  118  is then glued to a lower-lower layer  120  and a second pair  146  of end supportive portions and side rails  148  are glued in position to from the mattress  110 . The side rails  148  and the end rails  128 ,  146  extend from beneath the upper layer  112 .  FIG. 10  illustrates the component parts of the mattress  110 . 
     Several further preferred embodiments are illustrated in Figures to  11  to  18 . 
     In a further preferred embodiment the mattress is provided with a washable certified organic cotton cover. This advantageously allows the end user to keep the mattress cover clean and healthy. Skin cells and dust mites can be removed and the mattress can be advantageously aired. 
     Thus it will be apparent that there has been described an advantageous mattress that is designed to promote beneficial posture when sleeping and which is considered to reduce localised pressure on the entire body. 
     Further advantages and preferred features will be apparent from a reading of the specification as a whole. Other advantageous features are shown in the drawings. 
     It is to be recognised that various alterations and equivalent forms may be provided without departing from the spirit and scope of the present invention. This includes modifications within the scope of the appended claims along with all modifications, alternative constructions and equivalents. There is no intention to limit the present invention to the specific embodiments shown in the drawings. The present invention is to be construed beneficially to the applicant and the invention given its full scope. 
     In the present specification, the presence of particular features does not preclude the existence of further features. The words ‘comprising’, ‘including’ and ‘having’ are to be construed in an inclusive rather than an exclusive sense.