The effects of psychological distress on the health measures are virtually identical when perceived crowding rather than lack of privacy is used as a measure of subjective crowding. Given the confined nature of the household and the amount of time most people spend in it, there are three compelling reasons to believe crowding may affect one's health in a deleterious way. First, compressed living conditions can be viewed as constituting a source of chronic stress. Secondly, if any one of them contracts an infectious disease, it may be easily transmitted to others in the household. Thirdly, crowded housing units are more likely to be of poorer quality and be characterized by deficiencies that could have health consequences. Just as with sexual and reproductive behavior, some of the evidence concerning the connection between crowding and health is based on studies of lower animals.