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Spring forward. Fall back.��

For 60 years, most of the U.S. has engaged in this biannual clock-changing ritual, much to the chagrin of critics who have argued that it’s confusing, outdated and dangerous.��

The , passed by the U.S. House of Representatives in July, would end this practice, enabling states to stick with daylight saving time (DST) year-round. ��

Another recently introduced proposal, the , calls for the opposite: making standard time—which currently goes from November to March—the permanent national default. This proposal would still allow states to pass laws opting into permanent daylight saving time (pDST).

Under permanent standard time (pST), our winters would stay the same. But in the summer, the sun would rise and set earlier. For instance, in Denver, sunrise in June would occur as and set as early 7:23 p.m.

Which is better? Or should we just keep switching our clocks?

Ken Wright

“If we take a pure health, safety and well-being perspective, especially for our children, the clear choice based on all the available evidence is permanent standard time,” said Ken Wright, an integrative physiology professor of distinction and director of the Sleep and Chronobiology Lab at 91��ý. “Permanent daylight saving time, which is being considered the most right now, is the worst choice.”

We spoke with Wright about the potential health impacts of making DST permanent and why other options may be healthier.

When was daylight saving time invented?

It was first introduced on a large scale by the Germans during World War I. The idea was that extending evening sunlight would mean people wouldn’t use as much energy and that savings could be used to support the war effort. Several countries, including the U.S., followed suit temporarily during World Wars I and II. It wasn’t until 1966 that uniform start and stop dates for daylight saving time nationwide.

Have we tried to make DST year-round before?

�۱��.��During the oil crisis in 1974, but it was a very short-lived experiment. As soon as we hit the winter months, the public said, "No, we don't like these dark winter mornings," so Congress repealed it.

Why is permanent standard time your first choice?

Standard time is more closely aligned with the natural patterns in the environment under which we, as humans, have evolved. For instance, under standard time, we get lots of morning light, and the sun is high in the sky above us around noon. Under daylight saving time, there’s less morning light and the sun is high in the sky when the clock says 1 p.m.—after midday. We basically have a mismatch between the clock on the wall and the natural environment.

Why is morning light so important?

Light synchronizes our circadian rhythms (biological clocks that control an array of bodily processes) and our sleep timing to the 24-hour day. Morning light sets our circadian rhythm early, activates our brain, alerts us that it’s time to be awake and makes our mood better. But if we get that light at night it can shut down our melatonin (a hormone that signals us to sleep) and keep us awake.

What concerns you about permanent DST?

It would lead to darker mornings and brighter evenings, and this pushes our sleep times and our circadian rhythms later. We know that the later our sleep and circadian rhythms are, the less we sleep, the less healthy we are.��

For instance, insufficient sleep and waking up and going to sleep later increases our risk for obesity, heart disease, mental health disorders and substance use disorders. For children, if their internal clock is set later, it makes it more difficult for them to learn in school. The same goes for people’s performance at work, especially in the morning.

What would permanent DST look like in Colorado?

This change would cause Colorado to lose 2.4 months of having sunlight in the morning before 8 a.m. and four months of having sunlight in the morning before 7:30 a.m., compared to a permanent standard time system.������

The sun would rise late—after 7:30 a.m.—on 38% of school days, under permanent daylight saving time. Under permanent standard time, there would be no school days with a sunrise after 7:30 a.m. Under the current bi-annual change, Colorado has only four days with a sunrise after 7:30 a.m., so permanent daylight saving time is really a drastic change that will have consequences.

What concerns you about those dark mornings?

A lot of our children are going to be waiting for the school bus or walking to school in the dark. A lot of people are going to be driving to work or the ski slopes in the dark. These conditions could increase accidents.��

Also, many places have adopted late school start times because they recognize the benefits to our children—it allows them to be more in sync with the sunrise and shift their circadian rhythm and sleep timing earlier. There’s less absenteeism, better grades and students are falling asleep less in class. With permanent daylight saving time, we would lose all those benefits.

Why not just stick with the time change twice a year?��

There is no question the change itself is associated with problems. In the days after the "spring ahead," we get less sleep and wake up at a time when our brains are telling us we should still be sleeping. There are lots of associated risks, including��an increase in fatal motor vehicle accidents��and in and strokes.

That said, there are strategies that we could think about to reduce the negative impacts of the time change. Instead of having the change occur in the early morning hours on Sunday, what if we shifted it to Saturday morning so most people would have an extra day to adjust?����

What's your takeaway for lawmakers?

If you look across the board, not only at societies that focus on sleep, but also on��, it's nearly unanimous. Everyone says that permanent standard time, if we're going to make a change, is going to be the healthier, safer choice. Arizona and Hawaii have used permanent standard time since the 1960s, as federal law currently allows states the freedom to choose permanent standard time. We all should follow suit.