Abstract: A sleeping bag having double shells, an inner shell and an outer shell both open at one and the same side, each preferably differentially cut so that the sleeping bag is narrow at the bottom or foot end than at the upper end, and having insulating material between said shells, said shells being closed along said open side by a pair of off-set slide fasteners, said off-sets providing effective closing off of any leakage through the fasteners of the warmed air inside the sleeping bag and the entry of cold air from the outside and providing both a dead air space between said double fasteners and insulated pads to cover the two closures.