Simple evening habits may influence cardiovascular health more than previously understood. New research from Northwestern Medicine indicates that aligning overnight fasting with the body’s natural circadian rhythm can improve heart and metabolic function, even when calorie intake remains unchanged.
The findings suggest that avoiding food for several hours before sleep may be sufficient to produce measurable benefits.
Study findings on meal timing and sleep alignment
According to the researchers, middle-aged and older adults at increased cardiometabolic risk benefited when they extended their overnight fasting window by approximately two hours. Participants also avoided eating and dimmed lights for three hours before going to bed.
These relatively straightforward changes were associated with measurable improvements in markers of cardiac and metabolic function, both during sleep and the following day.
The researchers stated that synchronising fasting periods with the natural sleep–wake cycle may improve coordination between the heart, metabolism and sleep, thereby supporting cardiovascular health.
The findings were published in Arteriosclerosis, Thrombosis, and Vascular Biology, the scientific journal of the American Heart Association.
Cardiometabolic health and long-term risk
Cardiometabolic health is a key indicator of overall wellbeing. When compromised, the risk of chronic conditions such as type 2 diabetes, non-alcoholic fatty liver disease and cardiovascular disease increases.
Intermittent fasting has gained attention in recent years, with studies suggesting improvements in cardiometabolic indicators. However, most previous research focused on fasting duration rather than whether the fasting window aligns with the natural sleep cycle, which appears to be critical for metabolic regulation.
With participant adherence reaching nearly 90 per cent, researchers consider adjusting intermittent fasting around the sleep period to be a realistic and accessible intervention, particularly for middle-aged and older adults at elevated cardiometabolic risk.
The research team plans to refine the protocol and expand trials into larger, multi-centre studies.
Improvements in blood pressure, heart rate and glucose control
The 7.5-week study compared individuals who stopped eating at least three hours before bedtime with others who maintained their usual eating schedule.
Those who adjusted meal timing demonstrated notable improvements. Night-time blood pressure decreased by 3.5 per cent, while heart rate fell by 5 per cent. These changes reflected a healthier daily pattern, with higher blood pressure and pulse during the day and lower levels at night, patterns associated with improved cardiovascular function.
Participants also showed improved daytime glucose control. When administered glucose, their pancreas responded more effectively, indicating improved insulin secretion and more stable blood sugar levels.
The trial involved 39 overweight or obese adults aged 36 to 75. Participants were assigned either to an extended overnight fasting group of 13 to 16 hours or to a control group maintaining a usual fasting window of 11 to 13 hours. Both groups dimmed lights three hours before sleep. In the intervention group, 80 per cent of participants were women.