Firefighters are the heroes of our society, protecting us around the clock. But those 24-hour shifts are hard on the body, and even affect our cells.
Almost every cell in the body has a 24-hour biological clock that produces circadian (daily) rhythms. These rhythms regulate behavior (e.g., when to be active and when to rest) and physiology (e.g., blood pressure, blood sugar, muscle function). Circadian rhythms coordinate with the environment in part by regular, timed cycles of light and dark and eating and fasting. Disruptions to these cycles, which can occur with shift work, can impact health, leading to increased risk for obesity, heart disease, diabetes, and cancer.
Scientists from the Salk Institute and UC San Diego Health, in collaboration with the San Diego Fire-Rescue Department, conducted a clinical trial and found that time-restricted eating improved measures of health and wellbeing in firefighters. The lifestyle intervention only required the firefighters to eat during a 10-hour window and did not involve skipping meals.
The new findings may also have implications for shift workers, such as military personnel; health care, food service, and transportation professionals; telecommunications staff; and new parents, whose schedules often mimic shift work when caring for a new baby.
“Doctors and researchers are always thinking about the magic pill that can cure or reduce disease,” says Salk Professor Satchidananda Panda, co-corresponding author of the study and holder of the Rita and Richard Atkinson Chair. “It’s not a pill, but a healthy habit called time-restricted eating that can significantly reduce disease risk without any adverse side effects.”
Nearly 30 percent of Americans are considered shift workers, in which the individual must stay awake for two to three hours between 10:00 p.m. and 5:00 a.m. for at least 50 days a year. Increasing sleep and reducing calorie intake are often difficult, but previous studies have suggested that time-restricted eating (eating only within a certain window of time) may offer a simple behavioral change to improve health.
In this clinical trial, 150 firefighters from the San Diego Fire-Rescue Department used the myCircadianClock app on their phones to track their eating for three months. Half the group ate within a 10-hour window, while the other half (the control group) changed nothing and ate within a 14-hour window. Both groups were encouraged to follow a Mediterranean diet, which is known to have health benefits. The study included both individuals who were healthy and those who were overweight or who had health conditions such as high blood pressure, cholesterol, and/or blood glucose.
The researchers found that time-restricted eating within a 10-hour eating window was feasible without adverse effects and helped the firefighters significantly decrease their VLDL (“bad”) cholesterol size by 1.34 nanometers (small VLDL is less likely to block arteries), improve their mental health, and reduce their alcohol intake by roughly three drinks per week. Time-restricted eating also significantly improved blood sugar and blood pressure in firefighters who had elevated levels at the start of the study. The researchers concluded that time-restricted eating may provide even greater benefit for those at risk for cardiometabolic disease and other chronic diseases.
According to the researchers, these findings can likely be extended to a wider population, including many shift workers and others who experience abnormal sleep-wake patterns.
For more information about the Salk Institute, visit: www.salk.edu