Daylight saving time, early school start times cost billions in lost productivity, health care expenses

By Joanna Fong-Isariyawongse for The Conversation

Pittsburgh (US): Investigations into the 1986 Space Shuttle Challenger disaster revealed that key decision-makers worked on little sleep, raising concerns that fatigue impaired their judgment. Similarly, in 1989, the Exxon Valdez oil spill resulted in a massive environmental catastrophe. The official investigation revealed the third mate, in charge of steering the ship, was running on too little sleep, among other problems.

While these specific disasters were not caused by daylight saving time, they are conclusively linked to fatigue, based on postaccident investigations and reports. They underscore the well-documented dangers of sleep deprivation and fatigue-related errors. Yet a vast body of research shows that every year, the shift to daylight saving time needlessly exacerbates these risks, disrupting millions of Americans’ sleep and increasing the likelihood of accidents, health issues and fatal errors.

Imagine a world where one simple decision – keeping our clocks aligned with the natural cycle of the Sun – could save lives, prevent accidents and improve mental well-being. It’s not just about an hour of lost sleep; it’s about how small disruptions ripple through our health, our workplaces and even our children’s futures.

I’m a neurologist who specialises in sleep health. I’ve seen firsthand the negative impacts of poor sleep; it has enormous personal and economic consequences.

Yet despite overwhelming research supporting better sleep policies – such as delaying school start times to align with adolescent biology and the adoption of permanent standard time – these issues remain largely overlooked in public policy discussions.

Sleep deprivation comes with real costs

Chronic sleep deprivation does more than leave people tired. It costs an estimated US$411 billion annually in lost productivity and health care costs. Poor sleep leads to workplace mistakes, car accidents and long-term health issues that strain businesses, families and the economy as a whole.

Fortunately, there’s a fix. Smarter sleep policies – such as permanent standard time and later school start times – can boost efficiency, improve health and save lives.

Up before dawn

Teenagers are the most sleep-deprived age group in the U.S. Multiple studies and surveys show that anywhere from 71% to 84% of high school students report getting insufficient sleep.

This is largely due to early school start times, which force teens to wake up before their biological clocks are ready. If you have a teenager, you probably see it every day: The teen struggling to wake up before sunrise, rushing out the door without breakfast, then waiting in the dark for the school bus.

More than 80% of public middle and high schools in the US start before 8:30 am, with 42% starting before 8 am and 10% before 7:30 am. As a result, some districts have bus pickups as early as 5 am.

Teenagers are going through a natural shift in their circadian rhythms by about two hours. This shift, driven by hormones and biology, makes it hard for them to fall asleep before around 11 p.m. The bodies of teens aren’t wired for these schedules, yet schools and society have designed a system that forces them to function at their worst.

Declining scores, drowsy driving and depression

Sleep-deprived teens have lower grades and test scores, more car crashes caused by drowsy driving, more alcohol and drug use and higher rates of depression, anxiety suicide and aggressive behaviour, including carrying weapons.

Along with the health benefits, studies have found that moving school start times to 8:30 am or later could add $8.6 billion to the economy within two years, partly by increased graduation rates.

While concerns about increased transportation costs exist, such as the need for additional buses or drivers due to staggered school start times, some districts have found that optimizing bus routes can offset expenses, making the change cost-neutral or even cost-saving.

For instance, a study in Boston found that reorganising bus schedules using advanced algorithms reduced the number of buses needed and improved efficiency, which allowed high school students to start later and better align with their natural sleep cycles. This change not only supported adolescent sleep health but also saved the district $5 million annually.

More heart attacks, car wrecks and suicide

Every March, most Americans shift their clocks forward for daylight saving time. Studies show this change disrupts sleep and leads to measurable adverse outcomes, including a significant increase in heart attacks. These effects linger for days after the shift, as sleep-deprived workers struggle to adjust.

The mental health impact is also severe. Suicide rates increase in the weeks following the switch, particularly for those already vulnerable to depression.

Unlike daylight saving time, standard time follows the body’s natural circadian rhythm, which is primarily regulated by exposure to sunlight. Our internal clocks are most stable when morning light exposure occurs early in the day, signalling the body to wake up and regulate key biological functions such as hormone production, alertness and metabolism. In contrast, daylight saving time artificially extends evening light, delaying the body’s release of melatonin and making it harder to fall asleep at a biologically appropriate time.

Studies have found that adopting permanent standard time could prevent up to 5,000 suicides annually by reducing seasonal depression, decrease errors, injuries and absenteeism in the workplace and make roads safer, potentially preventing 1,300 traffic deaths each year.

Times are changing

The US tried permanent daylight saving time in 1974. It was so unpopular that Congress repealed it within nine months.

Russia tried it too, in 2011, but switched back three years later. The United Kingdom dropped permanent daylight saving time in 1971 after three years, and Portugal in 1996 after four. All of these countries found that the switch caused widespread public dissatisfaction, health concerns, more morning car accidents and disrupted work schedules. No country is currently on year-round daylight saving time.

These examples provide real-world evidence that permanent DST is undesirable due to public dissatisfaction, safety concerns and negative health effects – all three countries attempted it and ultimately reversed course. Since 2022, there has been renewed debate, largely driven by former U.S. Sen. Marco Rubio’s Sunshine Protection Act, which aims to make DST permanent.

However, the name is misleading because it doesn’t “protect” sunshine but rather eliminates critical morning light, which is essential for regulating circadian rhythms. Major health organizations, along with the National Safety Council, strongly oppose permanent DST due to its well-documented risks.

There are signs that suggest the US is finally waking up to these problems. Out of 13,000 school districts, 1,000 have independently adopted later school start times. California and Florida have enacted laws requiring high schools to start no earlier than 8:30 am California’s mandate went into effect in 2022, and Florida’s is set to begin in 2026.

Permanent standard time and later school start times are not radical ideas. They’re practical, evidence-based solutions based on human biology. Implementing these changes nationally would require congressional action. However, current federal law already allows states to adopt permanent standard time, as Arizona and Hawaii have done, setting a precedent for the rest of the country.

(The author is Associate Professor of Neurology, University of Pittsburgh)