EXERCISE AND PSYCHOLOGICAL HEALTH   DANIEL M. LANDERS ARIZONA STATE UNIVERSITY   The research literature derived from hundreds of studies with thousands of subjects now indicates that there is considerable evidence to support the claim that exercise is related to a relief in symptoms of depression and anxiety.  It is extremely unlikely that these overall relationships could be due to behavioral artifacts since these relationships are also found in behavioral studies with animals and with physiological measures that are known to be related to anxiety and depression.  The variables moderating the relationship between exercise and reduction in anxiety and depression will be discussed.  For example, moderating variables for anxiety show that anxiety is reduced more if the exercise is aerobic, if subjects engage in chronic exercise for more than 15 weeks, and if subjects have lower levels of fitness or higher levels of anxiety.  More research is needed to determine if this overall relationship is causal, and there is also a need to further examine some of the variables that are believed to moderate or explain the overall relationship.  For other variables related to positive mental health, the initial quantitative reviews of the literature have shown evidence that is promising.  At the present time, it appears that aerobic exercise enhances positive mood and self-esteem, produces more restful sleep, and increases cognitive functioning.  However, the overall relationships between exercise and positive mood and exercise and cognitive functioning could potentially be due to behavioral artifacts, and more research is needed to examine this.  For some of the psychological variables, particularly reduction in anxiety and depression following acute or chronic exercise, there is now sufficient evidence to justify stronger statements than currently exist in the 1996 Surgeon General's Report on Physical Activity and Health.