Although mid-life crisis has lately received more attention in pop culture than serious research, there are some theoretical constructs supporting the notion. Jungian theory holds that midlife is key to individuation, a process of self-actualization and self-awareness that contains many potential paradoxes. Although Carl Jung did not describe midlife crisis per se, the midlife integration of thinking, sensation, feeling, and intuition that he describes could, it seems, lead to confusion about ones life to date and ones goals. Later, Erik Erikson held that in lifes seventh stage, middle adulthood, people struggle to find new meaning and purpose to their lives; their questioning, he believed, could lead to what we now call a midlife crisis. Neither Jung nor Erikson were practitioners of medical psychiatry.

Some people have challenged the existence of mid life crises all together. One study found that 23% of participants had what they called a "mid-life crisis," but in digging deeper, only one-third of those -- 8% of the total -- said the crisis was associated with realizations about aging.

The balance (15% of those surveyed) had experienced major life experiences or transitions such as divorce or loss of a job in middle age and described them as "midlife crisis." While there is no doubt these events can be traumatic -- the associated grief reactions can be indistinguishable from depression -- these upheavals arent unique to middle age and arent an age-related midlife crisis.

University of California - Davis researchers Carolyn Alwin and Michael Levenson presented the current view of midlife crisis in a 2001 article:

Costa and McCrae (1980) found little evidence for an increase in neuroticism in midlife ... While they did find that some people were likely to experience such crises, ... these individuals were likely to experience crises in their 20s and 30s, and these experiences were not unique to midlife.
...Robinson, Rosenberg, and Farrell (1999) reinterviewed (500) men. Looking back over their midlife period, it became evident that while not necessarily entailing crisis, it was a time for reevaluation."

Wrapping up their review of mens midlife crisis, Alwin and Levenson wrote that "... Given the bulk of the data, it is likely that, for most men, midlife is a time of achievement and satisfaction. For a certain proportion of men, however, the passage is not at all smooth." They found a similar pattern when they reviewed research on what are commonly thought to be triggers for womens midlife crisis: menopause, children leaving home, the "sandwich" of caring for both parents and children. Most women navigated those periods without a traumatic psychological "crisis."

The enduring popularity of the midlife crisis concept may be explained by another finding by Robinson et al. As Alwin and Levenson summarize: "... younger men, now middle-aged Baby Boomers, used the term "midlife crisis" to describe nearly any setback, either in their career or family life."

Levinsons findings were research about the possible existence of a mid-life crisis and its implications. Whereas Levinson (1978) found that 80% of middle-aged participants had a crisis, and Ciernia (1985) reported that 70% of men in mid-life said they had a crisis (Shek, 1996) others could not replicate those findings including Shek (1996), Kruger (1994), and McCrae and Costa (1990). The debate of whether or not there is a mid-life crisis is being answered through recent research that attempts to balance such things as response bias and experimenter effects in order to establish internal validity. The above mentioned research does not support Levinsons model of a single age in the middle years that is a designated time of transition and potential "crisis."

For the most part, at all ages researchers in Positive Adult Development have found improvement or at worse stasis for most of the population.