Daylight savings time, which starts on March 8, entails more than simply moving the clock ahead 1 hour in most US states, countries in Europe, and elsewhere around the world. The shift affects the body’s biological clocks and circadian rhythms as well, and with them, our physiology, sleep routines, eating habits, and mood.

Impacts on Gut Health, Obesity

The shift to daylight savings affects all body systems, including the gut, where it can trigger irritable bowel syndrome, indigestion, and bloating. One study from Germany found that switching to both daylight savings time and to standard time increased the frequency of medical leaves due to ulcerative colitis and Crohn’s disease. The authors concluded that although the absolute changes in frequency were modest, the findings “indicate a relevant effect of seasonal clock change on symptom severity of [inflammatory bowel disease] patients, forcing them to take a medical leave.”

The shift to daylight savings time also has implications for people living with obesity. “Most of the acute effects we’ve seen with this shift are cardiovascular,” chronobiologist Emily Manoogian, PhD, senior staff scientist at the Salk Institute for Biological Studies, La Jolla, California, told Medscape Medical News. “The sleep-wake pattern and cardiovascular regulation have strong circadian rhythms. For those living with obesity at high cardiovascular risk, even a 1-hour shift forward can tip them into having a heart attack or stroke when they may not have had it without the shift.”

“The switch to daylight savings time also affects glucose regulation, which will be compromised for 1-4 days following the shift ahead (the shift back to standard time does not have this effect),” said Manoogian, who is also chair of public outreach for the Society for Research on Biological Rhythms. The dysregulation is due largely to a temporal misalignment of melatonin.

“Melatonin naturally increases at night. It’s directly suppressed by light and so it helps you fall asleep. But it also functions to suppress insulin secretion,” she explained. “When you shift an hour ahead, melatonin levels are still pretty high when you wake up in the morning. It’s 7 AM by the clock, but your body still thinks it’s 6 AM and it may not be able to process the change yet. That’s why we usually recommend waiting an hour or so after you wake up before eating for at least a few days after the switch so your body can adjust.”

In addition, she advised, “People with diabetes who use a continuous glucose monitor should pay attention during that transition and monitor themselves a little more closely to avoid experiencing an adverse reaction.”

Five Ways to Help Your Body Adapt

“Light and food are the two biggest cues to your body,” Manoogian said. “Light synchronizes your brain clock and food synchronizes your body clock.” Therefore, making changes in when and what you eat, as well as when you go to sleep and get up, “can help you to adjust much faster and return to normal life.”

For a smooth transition, try the following:

Shift awakening and bed times. At least a few days prior to the start of daylight savings time, go to bed a little earlier each night and wake up a little earlier each day, so you don’t have to do that hour jump in 1 day. “For most people, daylight savings time is misaligned,” Manoogian said. “It’s dark when they have to wake up and it might still be light outside when they have to go to bed. It’s hard to just say, ‘I’m going to sleep an hour earlier today’ because your body doesn’t work that way.”

Instead, she advised, you can take the edge off the switch by trying to go to bed 10 minutes earlier for several nights before, so you have only a 20-minute jump on the day of the switch. Similarly, for when you have to wake up, “scoot 15 minutes back each day until you get back to your ‘normal’ time.”

Use naps strategically. If you’re feeling extra tired, a short nap can help you recharge without interfering with your nighttime sleep. A recent napping study showed that you might even get a boost in creativity and alertness afterward.

Eat breakfast and dinner in sync with the time change. Gradually shift when you eat for a few days before or after the switch. For example, delay breakfast in 20-minute or so increments over 2 or 3 days to make the change easier on your body, and do the same with dinner until your body is completely in sync with the (actual) clock.

Cut back on high-fat foods. A recent study showed that adapting to the new time is slower when consuming a high-fat diet. Simply from a functional point of view, Manoogian suggested eating a healthier first meal of the day for at least the first few days after the shift, especially if you don’t have the luxury of delaying your mealtime.

“Drop the latte and go with a black coffee,” she said. “Skip the donut and go for an omelet with an avocado — something to keep that glucose a bit lower.”

In addition, some research shows that generally, people are more likely to crave poor quality food later in the day. “Instead of craving salad, you’re craving chips and chocolate,” she said. “Fighting those urges can ease the transition to a time change and keep you healthier.”

Adjust early-morning workouts. If you’re accustomed to working out first thing in the morning, you might be sleep-deprived or have less energy for a few days after the time switch, Manoogian noted. Consider taking a day off from working out or doing a shorter workout on those days so you don’t have to wake up as early.

Also be aware that if you’re healthy and working out super early, the time switch probably won’t have much of an effect, she said. However, “If you have cardiovascular disease and you’re doing these early morning workouts to try to help with that, doing the workout at the wrong time might tip you over” into a cardiac event.

Stop the Switch

The American Academy of Sleep Medicine recently published a position statement that the US should eliminate seasonal time changes in favor of permanent standard time, which it said aligns best with human circadian biology. The statement concluded, “Evidence supports the distinct benefits of permanent standard time for health and safety, while also underscoring the potential harms that result from seasonal time changes to and from daylight saving time.”

Indeed, the authors of a recent modeling study that compared outcomes under various permanent US time policies concluded that it would be best to get rid of biannual switching altogether.

Marilynn Larkin, MA, is an award-winning medical writer and editor whose work has appeared in numerous publications, including Medscape Medical News and its sister publication MDedge, The Lancet (where she was a contributing editor), and Reuters Health.