Mattress with Adjustable Firmness

A mattress comprising:

• one or more layers of foam material;
• an adjustable air layer positioned adjacent at least one of the one or more layers of foam material, the adjustable air layer comprising:
• an air bladder;
• and
• an open-cell foam material positioned inside the air bladder and configured to bias the air bladder to an inflated position when the open-cell foam material is exposed to atmospheric pressure;
• and
• a valve system fluidically connected to the air bladder and configured to regulate the air bladder.

A substrate, comprising:

• a fluid bladder;
• a foam core disposed within the fluid bladder;
• one or more sensors in fluid communication with the fluid bladder;
• a valve having an open position allowing fluid communication between atmosphere and an interior of the fluid bladder and the foam core and a closed position blocking fluid communication between atmosphere and the interior of the fluid bladder and the foam core;
• and
• a processor configured to:
• detect, based on signals from the one or more sensors, presence of a subject on the substrate;
• in response to detection of the presence of the subject, set firmness of the substrate to a base firmness equalized with atmospheric pressure;
• in response to receiving a request to modify the firmness of the substrate from the base firmness to a requested firmness, set the firmness of the substrate to the requested firmness;
• detect absence of the subject on the substrate;
• and
• in response to detection of the absence of the subject, restore the firmness of the substrate from the requested firmness to the base firmness.