The Global Sleep Crisis: Why the World Is Getting Less Sleep Than Ever

In 1942, Gallup asked Americans how much they slept. The average answer was 7.9 hours. When the same question was asked in 2013, the answer had dropped to 6.8 hours. In the span of a single lifetime, humanity lost more than an hour of sleep per night—and the consequences are only now becoming clear.

Matthew Walker, a neuroscientist at the University of California Berkeley and author of Why We Sleep, doesn't mince words about what this means. "No aspect of our biology is left unscathed by sleep deprivation," he wrote. "It sinks down into every possible nook and cranny." The World Health Organization declared insufficient sleep a global public health epidemic. The U.S. Centers for Disease Control called it a public health problem. And yet, in most of the world, sleeping less is still quietly celebrated as a sign of ambition.

A Century of Lost Sleep

The shift didn't happen overnight. It crept in gradually, decade by decade, as the boundaries between work and rest dissolved. The invention of the electric light bulb in 1879 was the first major disruption—suddenly, the night was no longer a barrier to productivity. Factories could run around the clock. Offices could stay lit. The social pressure to use every waking hour intensified.

Then came television, then the internet, then the smartphone. Each technology pushed bedtime a little later. A 2016 study published in Current Biology analyzed sleep patterns in three pre-industrial societies—the Hadza of Tanzania, the San of Namibia, and the Tsimane of Bolivia—people who live without electricity or artificial light. They slept an average of 6.9 to 8.5 hours per night, with consistent sleep and wake times tied to temperature rather than light. They had almost no insomnia.

Modern industrial societies look nothing like this. A 2019 survey of 13 countries by Philips found that 62% of adults worldwide feel they don't sleep well. In the United States, the CDC estimates that one in three adults regularly gets less than the recommended seven hours. In Japan, the problem is so severe it has its own word: inemuri—the practice of sleeping in public places, on trains and in meetings, because workers simply don't sleep enough at home.

The Machinery of a Crisis

Understanding why we sleep less requires understanding what sleep actually is—and why it's so easy to sacrifice. Unlike hunger or thirst, sleep deprivation doesn't announce itself with sharp, immediate pain. It erodes slowly. Cognitive function declines gradually enough that most people don't notice. Studies have shown that people who sleep six hours a night for two weeks perform as poorly on cognitive tests as people who have been awake for 24 hours straight—but they report feeling only "slightly sleepy." The impairment is invisible to the person experiencing it.

This is part of what makes the crisis so insidious. "After ten days of six hours of sleep," Walker writes, "you are as impaired as you would be after going without sleep for twenty-four hours. Yet subjectively, you don't feel that bad." The brain, deprived of sleep, loses the ability to accurately assess its own impairment.

Technology has accelerated the problem in ways that go beyond simply keeping people awake longer. The blue light emitted by smartphones and tablets suppresses melatonin—the hormone that signals to the brain that it's time to sleep—by up to 50%. A 2014 study in PNAS found that people who read on an iPad before bed took longer to fall asleep, had less REM sleep, and felt more tired the next morning than those who read a printed book. The devices we carry to bed are, in a very literal sense, keeping us awake.

What It's Costing Us

The economic cost of the sleep crisis is staggering. A 2016 RAND Corporation study calculated that sleep deprivation costs the United States $411 billion per year in lost productivity—roughly 2.28% of GDP. Japan loses $138 billion annually. Germany, $60 billion. The United Kingdom, $50 billion. These numbers account only for lost work output; they don't include healthcare costs, accidents, or the long-term burden of chronic disease.

The health costs are harder to quantify but potentially far larger. Chronic sleep deprivation is now linked to an increased risk of heart disease, stroke, type 2 diabetes, obesity, depression, Alzheimer's disease, and certain cancers. A landmark 2010 study in Sleep found that people who consistently slept less than six hours per night had a 12% higher risk of dying from any cause compared to those who slept seven to nine hours. A 2018 study in Nature Communications found that sleeping less than six hours in midlife was associated with a 30% increased risk of developing dementia later in life.

The connection to Alzheimer's is particularly alarming. During sleep, the brain activates a waste-clearance system called the glymphatic system, which flushes out toxic proteins—including amyloid-beta and tau, the proteins that accumulate in Alzheimer's disease. When sleep is cut short, this cleaning process is interrupted. "The more nights you go without adequate sleep," Walker explains, "the more amyloid builds up." Whether this is a cause or a consequence of Alzheimer's is still debated, but the correlation is strong enough that some researchers now consider poor sleep a modifiable risk factor for dementia.

The Culture of Sleeplessness

Perhaps the most difficult aspect of the sleep crisis is cultural. In many societies—particularly in the United States, Japan, and South Korea—sleeping less is worn as a badge of honor. "I'll sleep when I'm dead" is a phrase that has been attributed to everyone from Benjamin Franklin to various Silicon Valley executives. The implicit message is that sleep is laziness, that the truly ambitious don't need it.

This attitude has real consequences. A 2016 study found that employees who slept less were perceived by their managers as more dedicated and hardworking—even when their actual performance was worse. The social reward for appearing to sacrifice sleep creates a perverse incentive to sleep less, regardless of the cost.

Some companies have begun pushing back. Nike, Google, and Ben & Jerry's have installed nap pods in their offices. Aetna, the insurance company, pays employees up to $500 per year for logging sufficient sleep. The NBA and NFL have hired sleep coaches. But these are exceptions in a culture that still largely treats sleep as optional.

Is There a Way Out?

Researchers who study the sleep crisis are cautiously optimistic that awareness is growing. The publication of Walker's book in 2017 brought the science of sleep to a mainstream audience in a way that hadn't happened before. The rise of sleep tracking devices—Oura rings, Whoop bands, Apple Watches—has made people more conscious of their sleep patterns, even if the data isn't always accurate.

But awareness alone won't solve a structural problem. As long as work cultures reward long hours, as long as smartphones sit on bedside tables, as long as school start times force teenagers to wake before their biology allows, the crisis will continue. The solutions, researchers argue, need to be systemic: later school start times, workplace policies that protect sleep, urban design that reduces noise and light pollution at night.

In the meantime, the science is unambiguous. Sleep is not a luxury. It is not laziness. It is, as Walker puts it, "the single most effective thing we can do to reset our brain and body health each day." The question is whether modern society is willing to act on that knowledge—or whether we'll keep trading hours of sleep for hours of productivity, not realizing that we're getting the worse end of the deal.

Sources: Walker, M. (2017). Why We Sleep. Scribner. RAND Corporation (2016). Why Sleep Matters. Gallup (2013). In U.S., 40% Get Less Than Recommended Amount of Sleep. Grandner et al. (2010). Sleep. Sabia et al. (2021). Nature Communications.