Roughly one in three American adults, about 37% of the population, regularly gets less than seven hours of sleep per night. Globally, an estimated 852 million adults have insomnia, representing 16.2% of the world’s adult population. The problem is even worse among teenagers: 77% of U.S. high school students don’t get enough sleep.
Sleep Deprivation in the U.S.
The CDC tracks sleep duration through its Behavioral Risk Factor Surveillance System, and the 2022 data puts the number at 36.8% of U.S. adults sleeping fewer than seven hours on a typical night. That threshold, seven hours, is the minimum recommended for anyone 18 and older. The figure has been creeping upward. In 2020, it was 35%. Among high school students, the trend is steeper: the percentage not getting at least eight hours rose steadily from 2009 to 2021, landing at 77% in the most recent survey year.
These numbers likely undercount the problem. They rely on self-reported sleep duration, and people tend to overestimate how long they actually sleep. Someone who lies in bed for seven hours but takes 30 minutes to fall asleep and wakes twice during the night is getting considerably less rest than they think.
The Global Picture
A systematic review published in 2025 estimated that 852 million adults worldwide meet the criteria for insomnia, with a global prevalence of 16.2%. Nearly half of those cases, roughly 415 million people, qualify as severe insomnia. These figures capture people with a clinical sleep disorder, not the broader category of people who simply cut their sleep short due to work, screens, or lifestyle. When you include everyone sleeping less than they need, the global number is far larger.
How Much Sleep You Actually Need
Sleep needs shift dramatically across a lifetime. Infants aged 4 to 12 months need 12 to 16 hours. Toddlers need 11 to 14, preschoolers 10 to 13, and school-aged children 9 to 11. Teenagers between 13 and 18 need 8 to 10 hours, which explains why that 77% statistic among high schoolers is so striking. Early school start times, homework loads, and late-night phone use all collide with a biological clock that naturally shifts later during puberty.
For adults from 18 onward, the recommendation is at least seven hours. That floor doesn’t decrease with age, despite the common belief that older adults need less sleep. What changes is the ability to stay asleep, not the underlying need.
Who Is Most Affected
Sleep deprivation doesn’t hit every group equally. Racial and ethnic minorities consistently report shorter sleep duration and poorer sleep quality than white adults, a pattern that holds for children and adolescents too. Socioeconomic disadvantage plays a major role: people working multiple jobs, living in noisy or crowded housing, or facing chronic financial stress have fewer opportunities for uninterrupted rest. These sleep disparities map closely onto disparities in chronic disease.
Shift workers face particularly high rates of sleep problems. The healthcare industry ranks third among all sectors for insomnia and short sleep duration, and studies of healthcare workers who rotate through night shifts find that roughly one in three develops shift-work sleep disorder. Prevalence estimates vary widely by country and role, ranging from 10% in some U.S. studies to nearly 75% among nurses in Pakistan. The common thread is that working against your body’s natural circadian rhythm makes consistent, restorative sleep extremely difficult.
What Sleep Loss Does to Your Body
Short sleep is not just about feeling tired the next day. It functions as an independent risk factor for several major chronic diseases. People who consistently sleep fewer than seven hours have higher rates of obesity, type 2 diabetes, cardiovascular disease, and depression. The relationship is dose-dependent: the less you sleep, the higher the risk climbs. Sleep is when your body regulates hunger hormones, clears metabolic waste from the brain, consolidates memories, and repairs cardiovascular tissue. Cutting that process short night after night creates a cumulative deficit that compounds over months and years.
Your immune system takes a hit too. Studies consistently show that people sleeping six hours or fewer are significantly more likely to catch a cold after viral exposure than those sleeping seven or more. Chronic sleep restriction also blunts the effectiveness of vaccines, meaning your body produces fewer protective antibodies after immunization.
The Cost of Drowsiness
Sleep deprivation carries a measurable economic toll. Harvard researchers estimated that insomnia alone costs the U.S. workforce $63.2 billion per year in lost productivity, averaging 11.3 lost workdays per affected employee. That figure captures only insomnia, not the broader population of people who are simply underslept.
On the road, drowsy driving caused 633 deaths in the U.S. in 2023. The National Highway Traffic Safety Administration estimated that in 2017, around 91,000 police-reported crashes involved drowsy drivers, leading to 50,000 injuries and nearly 800 deaths. Those numbers almost certainly undercount the real toll, since crash investigators often can’t confirm drowsiness as a contributing factor after the fact. Unlike alcohol, there is no breathalyzer for sleep deprivation.
Why the Problem Keeps Growing
Several forces are pushing sleep duration downward simultaneously. Artificial light, especially the blue-enriched light from phones and laptops, suppresses your brain’s production of the hormone that signals sleepiness. Longer commutes eat into both ends of the day. The gig economy and around-the-clock digital connectivity blur the boundary between work hours and rest hours. And culturally, sleep still carries a stigma of laziness in many workplaces, despite overwhelming evidence that it is essential infrastructure for both cognitive performance and physical health.
For teenagers, the situation is compounded by biology. Puberty shifts the circadian clock later, making it genuinely difficult for most teens to fall asleep before 11 p.m. When school starts at 7:30 a.m., eight hours of sleep becomes nearly impossible. School districts that have pushed start times to 8:30 a.m. or later have seen measurable improvements in attendance, grades, and car accident rates among teen drivers.