Across the country, come Sunday morning, a familiar scene will play out: millions of people will wake up in a groggy state of shock as they roll over and stare at their clocks, wondering why they feel so tired or how they managed to sleep in so late.
The culprit: daylight saving time, rung in by our yearly ritual of “springing forward” an hour, that will occur this Sunday at 2 a.m.
But the fallout goes beyond a few sluggish mornings — daylight saving time can have serious consequences for personal and public health, ranging from accidents to worsened mood disorders to even heart attacks. The Mercury News asked sleep experts throughout the Bay Area and beyond to explain what daylight saving time does to our health and why, and to give their tips for softening the blow of setting our clocks forward.
Daylight saving time was originally introduced in the U.S. as a wartime energy-saving measure during World War I and again during World War II, with the idea that citizens would use natural light instead of burning precious energy on the home front. California adopted the measure in 1949, then in 1966, Congress signed daylight saving into law, codifying our annual time shifts.
While farmers often get the blame for the lost hour, there’s little evidence they were the cause. In fact, the American Farm Bureau has dedicated several publications to “setting the record straight,” noting that farmers were some of the most vocal critics of the time shift.
“All the animals on the farm, they don’t care what the clock says,” said Jennifer Martin, former president of the American Academy of Sleep Medicine, sleep researcher at UCLA, and self-professed member of a farm family. “The benefits are very theoretical … but the harms, though, are not just theoretical.”
Springing forward is associated with all sorts of negative outcomes. Studies have pointed to a veritable smorgasbord of knock-on effects, including an increase in car accidents, heart attacks, strokes, and potential negative effects on blood pressure and — most obviously — sleep. Martin says these effects make mental health symptoms worse for those with depression and anxiety, and make things harder even for those without a mood disorder.
These downsides can be especially hard for teenagers, who naturally need more sleep and tend to sleep in later, and can also have a greater effect on elderly people, those who are already sleep deprived, and those who work at night. Places like the Bay Area that are on the western edge of the time zone are especially affected, since the sun rises later compared to other places in the time zone.
The surprising array of downsides come because our bodies — and those of many animals, plants, and even bacteria — are intricately linked to the day-night cycle, explains Carrie Partch, a scientist who studies circadian rhythm at the University of California, Santa Cruz. Over a billion years of evolutionary history has woven circadian rhythm into the fabric of our biology, affecting nearly every aspect of our bodies from when our metabolism works best to how our immune systems work and beyond.
While humans vary in exact sleep needs, we have a symphony of biological systems that work in concert to make sure that we are alert and can deal with challenges we face when the sun is up, and then rest and wind down at night, explains Partch. So messing with that rhythm can have profound consequences.
“When you go to daylight savings, you’re reversing the pattern. You’re swapping morning light out for evening light. So that makes no sense for us,” said Rafael Pelayo, a sleep specialist at Stanford Medicine. “We’re a sleep-deprived country to begin with, we don’t have an hour to spare.”
While some research suggests that we can fully adjust within a week or two, others suggest that because of this mismatch, we never fully adjust to the change.
So, with biology going against us, is there any chance for sleepy citizens? Erin E Flynn-Evans thinks so.
Flynn-Evans leads the Fatigue Countermeasures Laboratory at NASA Ames Research Center near Palo Alto. Part of her work is researching to help astronauts adapt to get good sleep in outer space, where there is no day-night cycle.
“This is actually a place where the space research that we do is really helpful for us living here on the surface of the Earth,” said Flynn-Evans.
She recommends starting the day with brighter, bluer light. In the absence of earlier sunlight, these lights help signal that it’s time to be awake, despite the discomfort of bright lights when we are sleepy. On the flip side, dimmer, warmer light towards the end of the day can help prepare our bodies to go to sleep at night. In general, she argues that maintaining good sleep hygiene — going to bed at a regular time and having a cool, dark, quiet sleep environment — can all help.
“It really does make a difference in helping to improve sleep,” she said.
Other experts interviewed recommend keeping in mind that the first few days will be especially hard, avoiding anything “mission critical” if possible for the first few days and keeping in mind that everyone will be a little sleepier and perhaps crankier as they adjust.
The experts spoke universally against daylight saving time, and their personal opinions line up with recommendations of the American Academy of Sleep Medicine, the National Sleep Foundation as well as multiple European medical boards that argue to abolish the time change and stick to standard time.
Technically, the California legislature could get rid of daylight saving time — or standard time, with the help of Congress — with a 2/3 vote, following the success of a 2018 proposition approved by nearly 60% of California voters. Since then, no bill has succeeded in garnering the support needed to do either, though State Senator Roger Niello has introduced a resolution this year, SB 51, asking the Legislature to move toward “legislation related to the permanent implementation of standard time.”
“I think that’s probably the best advice: when bills come up in your state to get rid of daylight savings time, write to your elected officials, and encourage them to support bills to stay on permanent standard time,” said Martin.
In the interim, we can do our best to adjust to the change and — sometimes — take advantage of it.
“Even knowing the costs of this as a scientist, some part of me still enjoys it when the sun sets a bit later,” said Partch. “We humans do all sorts of things that we know are bad for us — daylight saving time is just another thing on a long list.”
