Did turning the clocks back really help us sleep better? The truth about daylight saving time and its hidden health risks

As autumn deepens and the nights stretch longer, many people look forward to one of the season’s simple pleasures — that “extra hour” of sleep when the clocks go back. It feels like a small gift: more time in bed, a slower Sunday morning, and a cozy start to darker days. Yet, sleep experts say that this annual ritual may not be as beneficial as it seems.

While the autumn shift appears harmless, research shows that altering our clocks can trigger subtle yet real impacts on both mental and physical health. Studies have linked the change to increased rates of depression, disrupted sleep patterns, and reduced overall wellbeing. Although the springtime clock change — when we “lose” an hour — tends to be worse for our hearts and safety, the fall transition isn’t entirely free from risk.

The origins of a century-old time trick

Daylight Saving Time (DST) was introduced in the UK in 1916 during World War I as a wartime energy-saving measure. By shifting clocks forward in spring and back in autumn, the goal was to make better use of natural daylight and reduce reliance on coal and electricity.

The idea wasn’t originally British. It came from William Willett, a wealthy builder from Kent, who published a pamphlet titled The Waste of Daylight in 1907. Willett argued that changing the clocks would not only save energy but also improve public health and happiness. Supported by figures like Winston Churchill, David Lloyd George, and Arthur Conan Doyle, his idea eventually gained traction — though Willett himself died before seeing it put into practice.

Today, about 70 countries and a quarter of the world’s population still observe DST, including the U.S., where it was formally adopted in 1966.

When time shifts, your body pays the price

Modern research increasingly challenges the wisdom of continuing this 100-year-old tradition. The main culprit is our circadian rhythm — the body’s internal clock that synchronizes with daylight to regulate sleep, hormones, and mood.

According to Professor David Ray of Oxford University’s Sleep and Circadian Neuroscience Institute, “when people live their lives against the clock, even by one hour, the effects can accumulate.” He warns that misaligning internal and external time by just 60 minutes can subtly raise risks of fatigue, metabolic disorders, and mood disturbances.

Scientific studies back this up. A meta-analysis spanning several countries found a 4% increase in heart attacks following the springtime clock change. Other research links DST shifts to higher stroke risks, depressive episodes, and even more traffic accidents.

The reason? When clocks move forward in spring, people lose an hour of sleep and face lighter evenings that disrupt melatonin production — the hormone responsible for sleep. Darker mornings also make it harder to wake naturally, compounding exhaustion.

Although turning clocks backward in autumn grants an extra hour, research shows most people only sleep an additional 33 minutes on average before their routines re-adjust, meaning the perceived benefit is short-lived.

The emotional toll of darker days

Researchers in Denmark found that depressive episodes rose by 11% in the 10 weeks following the autumn clock change, likely due to reduced daylight exposure. Less sunlight affects serotonin levels, leading to what many experience as the “winter blues” or seasonal affective disorder (SAD).

Meanwhile, a London School of Economics study tracking 30,000 people over three decades found that while the autumn shift slightly improved mood and sleep duration, it wasn’t enough to offset the springtime harm. The researchers estimated that the cumulative effect of clock changes costs economies around €750 per person annually in lost productivity and health deterioration.

Should we end daylight saving time?

The European Parliament voted in 2019 to abolish daylight saving time, but implementation stalled amid disagreements over which standard time — summer or winter — should prevail. Most scientists favor keeping winter time, as it aligns better with human biology and natural light cycles.

As Dr. Emily Akkermans, curator of time at the Royal Observatory Greenwich, explains: “The clocks change to make the most of the daylight we get each year, but in reality, we neither gain nor lose time — only our balance.”

So, while the thought of an extra hour in bed feels comforting, the science suggests it’s little more than a temporary illusion. What your body truly craves isn’t clock manipulation, but consistent, natural sleep aligned with sunlight — something no time change can replace.

FAQs

Why do we turn the clocks back?
The UK turns clocks back every October as part of daylight saving time, a system designed during World War I to conserve energy and extend daylight hours.

Who invented daylight saving time?
William Willett, a British builder from Kent, proposed the idea in 1907 after noticing how much daylight was wasted while people slept.

Does turning the clocks back help our health?
Not significantly. Research shows that while the extra hour offers brief relief, the overall disruption to circadian rhythms can still cause fatigue and mood dips.

Is daylight saving time bad for our health?
Yes. Studies link DST to increased risks of heart attacks, strokes, depression, and reduced sleep quality, especially after the springtime clock change.

Will daylight saving time ever end?
Possibly. The EU voted to scrap it in 2019, though countries have yet to agree on whether to keep summer or winter time permanently.