In the early days of the COVID-19 pandemic, researchers struggled to grasp^[1] the rate of the virus’s spread and the number of related deaths. While hospitals tracked cases and deaths within their walls, the broader picture of mortality across communities remained frustratingly incomplete^[2].

Policymakers and researchers quickly discovered a troubling pattern: Many deaths linked to the virus were never officially counted^[3]. A...

About 10% of Americans say they have chronic insomnia^[1], and millions of others report poor sleep quality. Ongoing research^[2] has found that bad sleep could lead to numerous health problems, including heart disease^[3].

Dr. Julio Fernandez-Mendoza^[4] is a professor of psychiatry and behavioral health, neuroscience and public health sciences at Penn State College of Medicine. He discusses the need for sleep, why teenagers require...