Assessment of the effect of body pressure on the warmth retention in sleeping bags

Sleeping bags are a common type of personal protective equipment that maintains the individual's comfort during rest in an open environment. One of the main purposes of utilizing sleeping bags is protection against cold weather in order to prevent body heat loss. However, during use, the exertion of body pressure on the sleeping bag may impact its protective performance. In this study, the influence of body pressure on the thermal insulation of two sleeping bags containing solid and hollow polyester fibers was investigated with consideration of body pressure in the head, shoulder, hips, and feet regions. Moreover, the sleeping bag layer's thickness and compressibility variations were analyzed. The results revealed that both sleeping bag layers suffer from the thickness and thermal insulation reduction under body pressure, especially in the hip area. However, due to the entrapped air inside the fiber structure, hollow fibers presented enhanced thermal resistance.