Please allow 24 - 72 hours for your Mattress to regain its full shape. Any memory foam will expand faster in a warmer room. In cold temperature, at delivery, your mattress may take a bit longer to return to full sized from its compressed state.The expansion time of the mattress will vary as per the surrounding HYBRID MATTRESS IN A BOX—All the comfort and trusted quality of a Sealy hybrid mattress,and ready to use within 24 hours.Get the best of both worlds with a unique combination of support from fabric-encased coils and the conforming comfort of memory foam LAYERS OF COMFORT—A soft top layer of adaptive foam “hugs” you, while a base layer of responsive coils “holds” you for foundational support DURAFLEX COIL EDGE—Experience more durability, more sleeping area, and a better seating edge when you get out of bed with this reinforced coil border on the perimeter of the mattress