The main factors that determine the comfort and safety of use of furniture for reclining are as follows: air circulation, temperature on the surface of the mattress, moisture circulation, softness of the mattress and durability (Smardzewski et al. 2008).
During the daily duties and activities, when the human is at the so-called wakefulness phase, appropriate physical conditions are required for the proper functioning of each organism. It is similar during the sleep. Optimal conditions allowing for sufficiently long, healing and relaxing sleep are characterised by the following values:
• atmospheric pressure: about 785 mmHg,
• relative humidity of air: in the winter about 50 % and in the summer about 60 %, and
• temperature of the air in the room: 14-18 °C (Grbac 2006).
The proper ventilation of the mattress is provided by adequate base and frame, which construction is of vital importance in shaping the form of the mattress— especially its overall dimensions. Mattresses based on spring systems usually provide comfortable air circulation inside their structure. Changing the geometry of the bed, its deformation under the weight of the user promotes air circulation and refreshing of the mattress. Foam materials usually have a porous structure and, as a general rule, enable air circulation in the mattress. The exception is latex foam. Made of vulcanised rubber, it does not provide air migration and forces shaping of artificial channels during its production.