Abstaining from food three hours before bedtime could benefit heart health, according to a recent study by Northwestern University.
Extending an overnight fast for two hours, dimming the lights and not eating for three hours prior to sleep were shown to improve cardiovascular and metabolic health.
The results were observed among middle-aged and older adults, who are at a higher risk for cardiometabolic disease, as stated in a university press release.
Time-restricted eating has recently surged in popularity due to its potential to improve heart health and aid in weight loss, the researchers noted.
“But most studies have focused on how long people fast, not how their fast lines up with their sleep schedule — a key factor in metabolic regulation,” the study authors wrote.
The nearly eight-week study, published in the journal Arteriosclerosis, Thrombosis and Vascular Biology, examined 39 overweight and obese participants between 36 and 75 years old. The intervention group was made up of 80% women.
The participants completed either an extended overnight fasting intervention — 13 to 16 hours — or a “habitual fast” of 11 to 13 hours. Both groups dimmed the lights three hours before bedtime.
People who finished eating at least three hours before going to bed saw “meaningful improvements” compared to participants who continued with their usual eating routines.
Those improvements included a 3.5% drop in blood pressure and a 5% drop in heart rate, as well as a “more natural drop” in both measures during sleep, which is “an important sign of cardiovascular health,” the researchers found.
The fasting participants’ hearts also beat faster during the day when they were active and slowed at night during rest — a pattern that’s linked to better heart health.
Those who abstained from eating also had better daytime blood sugar control, meaning the pancreas responded “more efficiently” when challenged with glucose, “suggesting it could release insulin more effectively and keep blood sugar steadier.”
First author Dr. Daniela Grimaldi, research associate professor of neurology in the division of sleep medicine at the Northwestern University Feinberg School of Medicine, commented on these findings in a statement.
“Timing our fasting window to work with the body’s natural wake-sleep rhythms can improve the coordination between the heart, metabolism and sleep, all of which work together to protect cardiovascular health,” she said.
Grimaldi noted that she and her fellow researchers were “genuinely excited” about the consistent improvements shown.
“Seeing that a relatively simple change in meal timing could simultaneously improve nighttime autonomic balance, blood pressure dipping, heart rate regulation and morning glucose metabolism, all without calorie restriction or weight loss, was remarkable,” she told Fox News Digital.
Grimaldi noted that the three-hour pre-sleep fasting window is “critical,” because that’s when melatonin rises and the body transitions toward sleep, “a period when eating disrupts metabolism.”
Sleep expert Dr. Wendy Troxel, RAND Corporation senior behavioral specialist and a licensed clinical psychologist in Utah, emphasized the study’s high adherence rate, at nearly 90%.
“High rates of compliance suggest that this approach may be both feasible and sustainable in real life and could have a demonstrable impact on improving cardiometabolic health,” Troxel, who was not involved in the study, told Fox News Digital.
The findings add to growing research linking sleep and circadian rhythms to cardiovascular health, she added. “In fact, the American Heart Association now recognizes healthy sleep as one of its Life’s Essential 8 pillars for heart health.”
Limitations and future research
Looking ahead, the researchers plan to expand the study to larger, multi-center trials to determine whether the benefits persist or “translate into reduced cardiovascular events or diabetes.”
Future studies could also explore the potential benefits of extending time-restricted eating.
“We also want to test this specifically in people with hypertension or diabetes, [who] might benefit most,” Grimaldi shared. “And exploring how this combines with other behavioral interventions, like exercise or morning light exposure, could help us develop more comprehensive strategies for cardiometabolic health.”
The high percentage of women poses a study limitation, as it limits the ability to draw “definitive conclusions” about gender differences, Grimaldi acknowledged.
“We need studies powered to examine sex differences,” she said. “Additionally, our 7.5-week intervention was long enough to show physiological changes, but not long enough to see effects on weight or long-term health outcomes.”
Northwestern University reported that only 6.8% of adults in the U.S. had optimal cardiometabolic health from 2017 to 2018.
These conditions can lead to chronic illness, including type 2 diabetes, cardiovascular diseases and non-alcoholic fatty liver disease. Heart disease is the No. 1 global killer, according to the CDC.