This is due to the fact that there is little food (flying insects) for them to eat. If they stayed awake in a warm home, without hibernating, then they would starve. We can begin the bat exclusion process during the winter months.
Mean free path of molecules in a gas. The molecules in a gas are assumed to be in continuous random motion making collisions with each other and with the walls of the container. The mean distance that the molecules travel between one collision and the next is called the mean free path of the molecules.
A free radical is any atom or molecule that has 1 or more unpaired electrons and is therefore highly reactive, seeking to acquire electrons from other substances. Free radicals are normally scavenged from tissues by the antioxidant enzymes superoxide dismutase and glutathione peroxidase.