For the approximately 10% of middle aged adults who go through an age-related midlife crisis, the condition is most common ranging from the ages of 35-50 (a large study in the 1990s[5] found that the average age at onset of a self-described "mid-life crisis" was 46). Mid life crises last about 3-10 years in men and 2-5 years in women.

A midlife crisis could be caused by aging itself, or aging in combination with changes, problems, or regrets over:

work or career
spousal relationships
maturation of children
aging or death of parents
physical changes associated with aging