Your Circadian Clock and Weight Control
It’s 6:00 in the morning, sunlight is peaking through the bedroom window, the snoozed alarm begins ringing aloud, and the idea of waking up and opening the cocoon of blankets that is enwrapped to provide warmth seems impossible. Sound familiar?
The human body has an innate internal clock that influences our sleep and wake cycle, it is known as circadian rhythm. Many of our body’s physiological processes, such as metabolism, body temperature regulation, and hormones work in conjunction with our circadian rhythm. This rhythm signals the body to turn genes on and off depending on the time of day. For example, in the morning the body kickstarts metabolism and increases the hormone cortisol to provide us with energy to begin our day. In the evening, metabolism slows down and the hormone melatonin is released to get us ready for sleep so the body can focus on repair and regeneration.
How Does the Circadian Clock Affect Our Hormones?
The body stimulates two hormones that regulate our hunger and metabolism — grehlin and leptin. Both grehlin and leptin levels have been shown in research to be affected by our circadian rhythm and quality of sleep.
Grehlin is secreted by our stomach and signals the hypothalamus in the brain to stimulate appetite. In other words, when grehlin is high we feel more hungry and may eat more. In contrast, leptin is secreted by our fat calls and signals the hypothalamus that we are full.
A cohort study conducted by the University of Wisconsin Medical School found that getting less than 8 hours of sleep has a direct correlation with increased BMI. The study observed a 14.9% increase in grehlin, and 15.5% lower leptin in individuals who got 5 hours of sleep versus 8 hours. High levels of grehlin and low levels of leptin increases appetite and decreases signals to the brain to alert us that we are full. This can lead to excess caloric intake causing weight gain and increasing the risk of obesity and diabetes.
Keeping our circadian rhythm on the right schedule has a huge impact on our health. Unfortunately, in a society guilty of late night snacking, abundant blue light exposure and stress-filled mornings our circadian clocks are no longer functioning optimally.
Tips to Regulate a Healthy Circadian Clock?
The circadian clock is largely influenced by environmental factors, such as meal times and light exposure. This means there are certain actions we can implement to keep our circadian clock ticking correctly.
- Set a sleep schedule
- Step outside in the morning to get natural light
- Eat 3 balanced meals a day at consistent times, avoiding eating too close to bedtime; a good rule of thumb is to allow 12 hours between dinner and breakfast
- Get regular physical activity, but avoid exercising 1-2 hours before bed
- Limit caffeine in the late afternoon or evening
- Decrease use of technology and exposure to blue light 1-2 hours before bed
- Dim lights around the house in the evening time
- Set an evening routine — this will signal to your brain it is time to wind down
- Avoid naps during the day
Implementing the tips above can reset the circadian clock improving sleep, which can promote healthy weight management and reduce the risk of obesity, diabetes and other chronic disease.
Looking for more guidance on regulating your hunger hormones? Contact our registered dietitians at the Nutrition Professionals. Our RDN’s can assist you in a personalized plan to implement at home and additional strategies to address healthy weight management.
PLOS Medicine Journal, Short Sleep Duration Is Associated with Reduced Leptin, Elevated Ghrelin, and Increased Body Mass Index