Close the Kitchen Early for Better Heart Health
I’ve been known to tell my clients, “Sleep is good food”. Regardless of why they’re seeing me (weight loss, blood sugar control, or blood pressure reduction), I’m always encouraging sleep hygiene. Poor sleep is associated with both mental and physical impairment.
New research supports my quote! Research from Northwestern Medicine discovered that a tiny tweak in your nightly routine may protect your heart. Adults who quit eating and reduced light exposure three hours before bedtime, and increased their overnight fast by roughly two hours, experienced improvements in blood pressure, heart rate, and blood glucose control. This was seen without reducing calories.
The circadian rhythm is an important factor in controlling cardiovascular and metabolic function. Researchers at Northwestern Medicine evaluated whether an overnight fast that mimicked a person’s normal sleep-wake cycle could improve metabolic and heart health. The focus wasn’t on how much they ate, but the timing of intake.
The study discovered that middle-aged and older adults who are at higher risk for cardiometabolic disease saw benefits from adding two hours to their overnight fasting window. In addition, they avoided food and reduced light exposure for three hours prior to bedtime. The minor adjustments lead to significant improvements in heart and metabolic markers during sleep and throughout the next day.
"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," said first author Dr. Daniela Grimaldi, research associate professor of neurology in the division of sleep medicine at Northwestern University Feinberg School of Medicine.
Corresponding author Dr. Phyllis Zee, director of the Center for Circadian and Sleep Medicine and chief of sleep medicine in the department of neurology at Feinberg, notes, "It's not only how much and what you eat, but also when you eat relative to sleep that is important for the physiological benefits of time-restricted eating”.
Cardiometabolic Health Matters
Previous research found that less than 7% of U.S. adults had optimal cardiometabolic health in 2017 to 2018. Poor cardiometabolic health increases the risk of chronic conditions, including type 2 diabetes, non-alcoholic fatty liver disease, and cardiovascular disease.
Studies suggesting that time-restricted eating (TRE) can improve cardiometabolic risk factors and possibly match the benefits of calorie-restricted diets have made TRE popular. But, most studies have focused on how long people are fasting, instead of how well that fasting window correlates to sleep timing, which is vital to regular metabolic processes.
The study had a nearly 90% adherence rate, and the researchers believe that TRE aligned with a person’s sleep hygiene is an achievable, non-pharmacological way to improve the cardiometabolic health of middle-aged and older adults. The researchers plan on modifying the protocol and increasing testing in larger multi-center trials.
Blood Pressure, Heart Rate, and Blood Sugar Improvements
The 7.5 week study evaluated subjects who quit eating at least three hours before bed with individuals who continued their typical eating habits. Subjects who adjusted their meal timing experienced multiple health benefits.
Evening blood pressure dropped by 3.5%, and heart rate decreased by 5%. These changes reflected a healthier daily pattern, with heart rate and blood pressure increasing during daytime activity and dropping at night during rest. A stronger day-night rhythm is linked with better cardiovascular health.
Subjects also experienced improved daytime blood sugar control. When given sugar, their pancreas responded more effectively, suggesting improved insulin release and more regulated blood sugar levels.
The trial was small and included 39 overweight/obese subjects aged 36 to 75 years old. Subjects were assigned to an extended overnight fasting group (13 to 16 hours) or a control group, which continued their usual fasting window of 11 to 13 hours. Both groups reduced light exposure three hours before bedtime. The intervention group included 80% women.
Tips to improve sleep hygiene
· Stick to a sleep schedule. Go to bed at the same time each night and wake at the same time.
· Avoid heavy meals in the evening, which may lead to acid reflux and poor sleep.
· Brush your teeth after dinner to avoid snacking after dinner. This is a sign that “the kitchen is closed”.
· Limit alcohol in the evening, which interferes with quality sleep.
· Avoid caffeine after 2 PM if you suffer from insomnia. This includes caffeine from coffee, tea, energy drinks, and chocolate.
· Drink water or unsweetened seltzer water or decaffeinated tea instead of eating.
· Turn off screens at least three hours before bed. This includes TV, tablets, laptops, cell phones, and gaming devices.
· Don’t eat, do work, or use electronic devices in bed!
· Establish an evening routine for sleep. Read or meditate before bed to turn off your brain.
· Keep your room cool and quiet for best sleep.
Lisa Andrews, MEd, RD, LD
Reference:
Daniela Grimaldi, Kathryn J. Reid, Sabra M. Abbott, Kristen L. Knutson, Phyllis C. Zee. Sleep-Aligned Extended Overnight Fasting Improves Nighttime and Daytime Cardiometabolic Function. Arteriosclerosis, Thrombosis, and Vascular Biology, 2026; DOI: 10.1161/ATVBAHA.125.323355