Scientists have long known that what we eat affects our health, but new research suggests that when we eat may be just as important.
A study from Northwestern Medicine shows that adjusting meal timing to match the body’s natural sleep and wake cycle can improve heart and metabolic health, especially for middle‑aged and older adults who are at higher risk for disease.
Our bodies follow a natural 24‑hour rhythm called the circadian rhythm. This internal clock controls sleep, hormone release, digestion, blood pressure, and many other processes.
When eating patterns do not match this rhythm, the body can become stressed, which may increase the risk of heart disease, diabetes, and other chronic conditions. Late‑night eating, bright lights before bed, and irregular sleep schedules can all disrupt this system.
In this study, researchers tested whether extending the overnight fasting period and avoiding food before bedtime could bring health benefits. Importantly, participants did not eat fewer calories.
The focus was only on changing the timing of meals. The scientists asked volunteers to stop eating at least three hours before going to sleep and to extend their overnight fast by about two hours compared with their usual routine.
The results showed meaningful improvements. Participants who followed the new schedule experienced lower nighttime blood pressure and heart rate.
These changes indicate that the body was resting more effectively during sleep. A healthy pattern normally involves higher heart activity during the day and lower activity at night, allowing the cardiovascular system to recover.
Blood sugar control also improved. When participants consumed glucose, their bodies released insulin more efficiently, helping keep blood sugar levels stable. Better blood sugar regulation lowers the risk of type 2 diabetes and protects blood vessels from damage.
The study lasted about seven and a half weeks and included overweight adults aged 36 to 75. One group followed the extended fasting schedule of 13 to 16 hours overnight, while another group continued their usual eating habits. Both groups dimmed lights three hours before bedtime to reduce the impact of artificial light on the circadian rhythm.
Researchers believe these improvements occurred because eating earlier allowed the body to process food at a time when metabolism is naturally more active. At night, the body prepares for rest, and digestion slows down.
Eating late forces the body to work when it should be recovering, which can lead to higher blood pressure, poor sleep, and metabolic stress.
Cardiometabolic health refers to the combined health of the heart, blood vessels, and metabolism. Poor cardiometabolic health increases the risk of conditions such as heart attack, stroke, fatty liver disease, and diabetes.
Unfortunately, only a small percentage of adults achieve optimal cardiometabolic health, making prevention strategies especially important.
In reviewing and analyzing the findings, the study suggests that simple lifestyle changes may provide meaningful benefits without medication or strict dieting. Aligning eating habits with the natural sleep cycle appears to strengthen the coordination between sleep, metabolism, and heart function.
However, the study involved a relatively small number of participants and lasted only a few weeks, so larger and longer studies will be needed to confirm the results.
Even so, the research offers practical guidance. Avoiding late‑night meals, allowing the body time to digest before sleep, and maintaining a consistent daily schedule may help protect long‑term health. These habits are simple, low‑cost, and accessible to most people.
Overall, the study highlights how closely our health is tied to the body’s internal clock. It suggests that paying attention not only to what we eat but also to when we eat could play an important role in preventing heart disease and metabolic disorders as we age.
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