Fewer than one-fifth of Americans say they actually experienced a midlife crisis. And yet there are still some common misunderstandings people have about midlife. I study midlife, and especially how people in this stage of life experience sleep and stress. In my research, I have also found that midlife brings both opportunities and challenges. Are We There Yet? Exactly when midlife begins is hard to pin down. Compared with other developmental periods—such as childhood, adolescence, and older adulthood—midlife lasts longer and includes more diverse social roles. There are fewer published studies on midlife than studies on childhood and older adulthood. So researchers still know little about the timing and unique experiences of this stage of life. Midlife may begin at different times for different people. In the 1990s, people generally agreed that midlife began at age 35. This has shifted toward an older age. Now Americans might say midlife begins at age 44 and ends …