When it comes to turning back the clocks on our devices, technology has us covered. Our smartphones automatically adjust.
But our internal clocks aren't as easy to re-program. And this means that the time shift in the fall and again in the spring can influence our health in unexpected ways.
"You might not think that a one hour change is a lot," says Fred Turek, who directs the Center for Sleep & Circadian Biology at Northwestern University. "But it turns out that the master clock in our brain is pretty hard-wired, " Turek explains. It's synchronized to the 24 hour light/dark cycle.
Daylight is a primary cue to reset the body's clock each day. So, if daylight comes an hour earlier — as it will for many of us this weekend — it throws us off.
"The internal clock has to catch up, and it takes a day or two to adjust to the new time," Turek says.
And the results of a new study, which will be presented at an American Heart Association conference later this week, points to an increase in the number of patients admitted to the hospital for a atrial fibrillation, which is a type of irregular heartbeat, in the days following the spring time change.
"It is definitely a surprise when thinking about a one-hour difference," says Jay Chudow, an internal medicine resident at Montefiore Health System who did the research. This finding is preliminary, but it adds to the evidence that daylight saving time transitions can have negative health consequences.
These studies are a reminder of just how sensitive we are to time and rhythm. Over the last 20 years, scientists have documented that, in addition to the master clock in our brains, every cell in our body has a time-keeping mechanism. These clocks help regulate important functions such as sleep and metabolism. And increasingly, there's evidence that when our habits — such as when we eat and sleep — are out of sync with our internal clocks, it can harm us.
As we've reported, our bodies crave consistent routines. When we disrupt our routines with erratic sleep or eating habits, it can increase the risk of metabolic disease. For instance, people who work overnight shifts are at higher risk of developing diabetes and obesity. Research also shows that kids who don't have set bedtimes and mealtimes are also more likely to become overweight.
At this time of year, as the amount of daylight continues to decrease, it's easy to fall into bad habits. "The [decrease] in daylight can throw off a lot of things including socialization and emotional rhythm," says Sanam Hafeez, an adjunct assistant professor of psychology at Columbia University.
How to prepare for the darker days ahead
Go to bed an hour or so earlier. As the clocks turn back, Hafeez says you want to maximize your exposure to daylight in the morning hours, since it gets dark so early in the evening. If you're accustomed to going to bed at 11 p.m., try 10 p.m. instead. "Just record 'The Daily Show,' or whatever you watch at night. That's what I do," says Hafeez.
As we've reported, research has shown that a lack of sleep can send a signal to the body to store fat, so getting plenty of shut-eye is key to good health. And, if you use the morning for exercise, all the better, since physical activity can help stave off depression.
Stock up on foods that nourish. Our moods can take a turn south during the cold dark months, and we tend to eat more, too. So, instead of a big plate of pasta for dinner, think about adding protein sources. "There definitely seems to be more fullness associated with protein," Janet Polivy of the University of Toronto at Mississauga told us in 2011.
Fish, nuts and other plant-based proteins such as tofu are good alternatives if you don't want to add meat. Fatty fish like salmon and tuna are excellent sources of omega-3 fatty acids. "One of the most basic ways that omega-3s help to regulate mood is by quieting down the [body's] response to inflammation," Joe Hibbeln of the National Institutes of Health told us for a story on the Food-Mood connection.
Eat dinner early and keep it light. Research suggests that the timing of your meals can help stave off weight-gain. In one study, a group of dieters who ate their main meal of the day before 3 p.m. lost about five pounds more than the people who ate a dinner meal later in the evening.
So here's one approach: Make lunch your main meal, and take a small-plate, tapas approach to dinner. Also, limit alcohol. There's plenty of evidence that drinking more than a serving or two per day is not healthy.
Join a club or group activity. Winter can bring social isolation. "Some people tend to hibernate," Hafeez says. And some people develop seasonal depression. Bright lights or light boxes can help people who have seasonal affective disorder.
Another approach is to try to stay socially engaged. Hafeez's advice: Join a book club or find people with a shared hobby. Group exercise classes are also effective at combating the winter blues.
Go south — or closer to the equator — if you can. The farther north you live, the darker your days will be in the winter. And this can dampen your mood. Here's Fred Turek's advice: "I take more trips to the southern part of the U.S. during the winter months. The closer you get to the equator, the more daylight there is," Turek says.
Of course, for many of us, travel is a luxury, so this might not be possible, but it's important to get as much light into your day as you can.
RACHEL MARTIN, HOST:
If you woke up before your alarm went off this morning, it's no big surprise. Those of us who turned back our clocks over the weekend are still adjusting. NPR's Allison Aubrey reports that scientists are learning just how sensitive our bodies are to time.
ALLISON AUBREY, BYLINE: When we turn back the clocks in the fall or spring forward in the spring, the one-hour change may not seem like a big deal, but our bodies definitely notice. Daylight saving time is actually linked to an increased risk of traffic accidents, heart attacks and strokes.
JAY CHUDOW: It is definitely a surprise when thinking about one-hour difference causing significant health effects.
AUBREY: That's Jay Chudow. He's an internal medicine resident at Montefiore Health System. He says the bad effects that have been documented in studies are mostly linked to the spring forward change when we lose an hour of sleep. And he was curious to know how that might influence the risk of a heart condition known as atrial fibrillation or AFib. It's a type of irregular heartbeat. So he analyzed about 6,000 hospital admissions over an eight-year period.
CHUDOW: What we found when we took a look at people who were admitted to the hospital for atrial fibrillation was that linked to daylight saving time, there was a 20-percent increase in the number of admissions for atrial fibrillation in the days following spring transition. And it was surprising.
AUBREY: Chudow is set to present his research at an American Heart Association conference this week. The findings are preliminary, but they give insight into just how sensitive our bodies can be to time. Fred Turek is director of the Center for Sleep & Circadian Biology at Northwestern University. I asked him what's happening in our bodies and brains as we adjust to the time change.
FRED TUREK: You might think that one-hour time change is not a lot. But it turns out that the master circadian clock in our brain is pretty hardwired. It runs with a period of about 24 hours, and it's synchronized to the light-dark cycle.
AUBREY: And daylight is a primary cue to reset the clock. So if daylight comes an hour earlier or later, it throws us off.
TUREK: So all of a sudden, if you change the day by an hour, that internal clock has to catch up. It's going to take a day or two for it to readjust to the new time.
AUBREY: Turek says over the last 20 years, scientists have learned a lot about how our body clocks help regulate our biology. And it's not just the master clock in our brain. We have time-keeping mechanisms in every organ of the body. And increasingly, there's evidence that when our habits - such as when we eat and sleep - are out of sync with our internal clocks, it can harm us. Our bodies crave consistent routines. So when we disrupt them by, say, binge-watching late-night TV or midnight snacking or doing overnight shift work, there can be consequences.
TUREK: There's a great deal of research studies demonstrating that when we shift the biological clock and we shift the sleep-wake cycle - if that's done on a chronic basis, it leads to disease states such as obesity, diabetes and cardiovascular disease.
AUBREY: It doesn't happen overnight, but the risks increase the more your habits are at odds with your natural rhythms. At this time of year, as the amount of daylight continues to decrease, it can be easy to fall into bad habits. Psychologist Sanam Hafeez says especially in northern climates where it's cold and dark people are inclined to hibernate.
SANAM HAFEEZ: So that daylight change can actually really throw off a lot of things, including socialization, emotional rhythm. It sort of has a pervasive effect on some folks.
AUBREY: To combat the dark-day blues, Hafeez has three basic pointers. One, plan social gatherings in advance. Maybe join a club or a group linked to a hobby. Two, watch your alcohol consumption since drinking too much can amplify the pervasive effects. And three, go to bed an hour or so earlier so you can get up and maximize that exposure to sunlight in the morning hours. Allison Aubrey, NPR News. Transcript provided by NPR, Copyright NPR.