Scientists from Northwestern Medicine conducted an investigation into whether synchronizing an overnight fasting period with an individual’s inherent sleep-wake cycle could enhance cardiovascular and metabolic wellness. The body’s circadian rhythm holds a pivotal position in overseeing both heart-related and metabolic processes. Notably, the participants in this research did not cut back on their total calorie consumption at all. Instead, the emphasis was solely on modifying the timing of their meals throughout the day.
Results from the study revealed that adults in middle age and beyond, who were at increased risk for cardiometabolic disorders, experienced significant advantages by prolonging their nightly fasting duration by approximately two hours. In addition, they refrained from consuming any food and reduced lighting exposure for a full three hours prior to retiring for the night. Such modifications resulted in detectable enhancements in various cardiac and metabolic indicators, observable both during slumber and extending into the subsequent daytime hours.
“By aligning the fasting window with the body’s innate wake-sleep patterns, we can foster better synchronization among the heart, metabolic functions, and sleep mechanisms—all of which collaborate to safeguard cardiovascular well-being,” explained lead author Dr. Daniela Grimaldi, who serves as a research associate professor of neurology within the sleep medicine division at Northwestern University Feinberg School of Medicine.
These discoveries appeared in the February 12 edition of Arteriosclerosis, Thrombosis, and Vascular Biology, a publication affiliated with the American Heart Association.
“Beyond just the quantity and type of food consumed, the timing of meals in relation to sleep plays a crucial role in maximizing the physiological advantages of time-restricted eating practices,” noted senior author Dr. Phyllis Zee, who directs the Center for Circadian and Sleep Medicine and leads the sleep medicine section in the neurology department at Feinberg.
Understanding the Importance of Cardiometabolic Health
Previous statistics indicate that merely 6.8% of American adults achieved optimal cardiometabolic health between 2017 and 2018. Suboptimal cardiometabolic status significantly elevates the likelihood of developing persistent illnesses, including type 2 diabetes, non-alcoholic fatty liver disease, and various forms of cardiovascular disease.
Time-restricted eating has surged in popularity lately, as evidence points to its ability to positively influence cardiometabolic parameters, often delivering outcomes comparable to those from conventional calorie-limiting diets. That said, the majority of prior studies have primarily examined the length of fasting periods, overlooking the critical aspect of how those periods align with an individual’s sleep schedule—a factor essential for effective metabolic oversight.
Achieving close to 90% compliance in this experiment leads the researchers to conclude that tying time-restricted eating directly to sleep cycles could represent a practical, non-drug-based strategy, particularly beneficial for middle-aged and older individuals grappling with heightened cardiometabolic vulnerabilities.
Moving forward, the research group intends to perfect this methodology and conduct broader evaluations through expansive, multi-center clinical trials to validate and expand upon these initial findings.
Enhancements in Blood Pressure, Heart Rate, and Glucose Regulation
This 7.5-week experiment pitted participants who ceased eating at least three hours before bedtime against a control group continuing their standard eating routines. The individuals who shifted their eating schedule to earlier in the evening witnessed a range of substantial physiological improvements.
Specifically, their nighttime blood pressure levels fell by 3.5%, while heart rates diminished by 5%. These alterations promoted a more salubrious diurnal variation, characterized by elevations in heart rate and blood pressure amid daytime exertions and declines during nocturnal repose. A more pronounced day-night fluctuation in these metrics correlates strongly with superior cardiovascular outcomes.
Furthermore, the intervention participants exhibited superior blood glucose management during waking hours. Upon receiving a glucose challenge, their pancreatic response proved more robust, indicating enhanced insulin secretion and more stable glycemic profiles overall.
The study enrolled 39 adults classified as overweight or obese, ranging in age from 36 to 75 years. They were randomly allocated to either the extended overnight fasting cohort, which fasted for 13 to 16 hours nightly, or a control cohort adhering to their typical 11-to-13-hour fasting windows. Both cohorts implemented light dimming three hours before bedtime as a consistent measure. The treatment group comprised 80% women.
Support for this research came from the NIH/National Heart, Lung and Blood Institute, the National Institute on Aging, and the NIH/National Center for Advancing Translational Sciences (NCATS).
