Most people don’t function well with less than 7 hours of sleep, regularly getting less than that amount can, over time, harm your health. Continued sleep shortages contribute to depression, heart disease, lowered immunity, obesity, and type 2 diabetes, among other ills.

Why are so many of us sleeping so little? One reason is simple math: Americans are working longer—an average of 44 hours per week, according to an August 2015 Gallup Poll. That’s the longest workweek in the history of Gallup’s annual work survey. And a record 17 percent of U.S. adults now log 60 or more hours per week in the office, leaving less time for sleep.  Working longer hours, plus having longer commutes, leaves less time for domestic chores—paying bills, doing repairs, dealing with paperwork for taxes or kids’ college—which get stuffed into twilight hours.

In today’s global economy, working late into the night or first thing in the morning is often a necessity. That kind of shift work—once mainly confined to nurses, emergency room doctors, factory workers, and police officers—can wreak havoc on the body’s sleep-wake cycle.