The editor suggests that postbirth "blues" are not depressive disorders. Given that the blues are very prevalent and occur at about the same timing after birth, regardless of demographic variables, psychiatric history, or life stressors, she wonders if they are a normative rather than a pathologic condition. Citing flaws in previous studies' methodology that measure only sad moods and have no way of recording joy, she suggests that researchers should test the hypothesis that postpartum blues reflect "heightened reactivity," not depression. Could the blues be the demonstration of mammals' "unique neurobiological system that is activated by postpartum hormonal changes and that promotes the initial attachment behavior between mothers and newborn babies?"