Rachel Simmons is the author of "Enough As She Is: How to Help Girls Move Beyond Impossible Standards of Success to Live Happy, Healthy, Fulfilling Lives." Follow her on Twitter @racheljsimmons. The views expressed in this commentary are her own.
(CNN)At a moment when girls enjoy historic opportunity -- watching Chloe Kim and Mikaela Shiffrin soar to gold, and Oprah preach girl power from the Golden Globes stage -- teen girls tell researchers they are twice as depressed, anxious and stressed out as boys. And though girls beat out boys in college and graduate school admissions, according to a University of California-Los Angeles study, female college freshmen have never been lonelier or less happy.