How Circadian Metabolism Affects Healthy Aging

We all age, though how well varies from one individual to another. Whether we age gracefully, suffer from chronic illness, or live well beyond our life expectancy varies with many factors. Our genetics, activity levels, and how well-balanced our circadian metabolism remains throughout life all play a role in healthy aging.

Preserving a healthy circadian rhythm supports healthy sleep habits and proper metabolism, lessening one’s risk of chronic diseases, including metabolic (diabetes) and neurodegenerative (declining brain function) diseases.

Aging and the circadian rhythm

While age itself isn’t a disease, as we age, we become at higher risk for various chronic conditions, e.g., diabetes, heart disease, cancer, and obesity.

According to the World Health Organization (WHO), the world population older than 60 will rise from 12% to 22% between 2015 and 2050. Acosta-Rodriguez et al. state that the WHO estimates that globally, people suffer from diseases secondary to aging for over 10% of their life.

Most of us are familiar with the brain’s circadian rhythm, or 24-hour light and dark cycle. This helps guide our sleep-wake phases, and disruptions of it are known to trigger sleep disorders, among other health concerns. This biological clock is regulated by a part of the brain called the hypothalamus, helping to regulate feeding, body temperature, various hormones, rest, and activity. Additional areas in the brain (e.g., retina) and more distant tissues, such as the liver, also possess rhythmic (circadian) control. Together, these circadian clocks help maintain various body functions and metabolism.

A well-balanced circadian metabolism regulates health

One can age healthily by maintaining circadian rhythms through specific regulations in several body systems. But what do these body circadian (rhythmic) ‘clocks’ have to do with aging? These clocks are dynamic, meaning they change throughout our life as we age; even sleeping and waking patterns vary with age.

It is well established that disruptions to our central clock (in the brain) lead to daytime sleepiness, irritability, decreased focus or productivity, and increased risk of accidents and mistakes. However, the clocks found within organs outside the brain (peripheral tissues), like the liver or heart, are regulated not by light and darkness but by metabolism, sensitive to feeding or fasting. When regular fasting and feasting phases don’t mesh with normal light and darkness activities, metabolism may become skewed, leading to diseases like heart disease or diabetes.

Almost every cell in our body has an internal clock that lasts about 24 hours. The main clock (in the brain) adjusts with subtle changes to cues received. Still, the peripheral biological rhythms are more heavily influenced by nutrition. Even so, the close coordination of light and dark, when we eat and our environment, helps to regulate our circadian rhythm. Any alterations can lead to changes in our microbiome (normal bacteria that live in our GI tract and help ensure healthy digestion). Additionally, changes can lead to alterations in insulin regulation, brain function, and more.

The liver and glucose regulation

While the brain portion of the clock is maintained and controlled by the suprachiasmatic nucleus (SCN), the master circadian clock, the peripheral regulation of glucose and energy primarily occurs via help from the liver and pancreas. This peripheral regulation plays a role in maintaining our energy balance (homeostasis). Thus, maintaining a circadian rhythm and proper metabolism helps lessen one’s chance of developing insulin resistance, obesity, and diabetes when kept in balance.

Heart function

Another example of circadian rhythm balance exists within the heart and its muscles. In the face of fasting or changes in light-dark effects on the body, the heart responds differently to various nutrients, such as glucose, fatty acids, and amino acids (building blocks of protein). Studies suggest a link between disruptions in the circadian clock in heart muscle tissue and an increase in one’s risk of heart disease. While additional research is needed, this suggests the potential for lessening the chance of heart disease by paying attention to circadian metabolism and ensuring it remains at peak function as we age.

Thus, maintaining a tuned circadian clock requires appropriate sleep/wake, feeding/fasting, and rest/activity cycles. The liver and heart represent only two tissues outside the brain whose circadian regulation occurs via the fasting/feeding cycles. These and other tissues, such as the pancreas, kidneys, and skeletal muscle, do not rely on light/darkness for proper function but instead on the triggers of eating healthy, eating meals alternating with fasting periods at appropriate times.

Meal timing and aging

Who eats at the same time every day? Who maintains the same eating patterns for life? Generally, very few people follow a rigid routine for life. However, studies suggest that not only do factors such as daylight and darkness play a role in maintaining our 24-hour rhythm, but consistent eating times each day help maintain this rhythm. As we age, this helps preserve one’s proper metabolic functions (chrononutrition) and may help lessen our chances of developing chronic diseases.

Maintaining a healthy circadian metabolism

Is it in our best interest to maintain healthy circadian rhythms? Studies indicate that doing so will enhance our organs’ health, increase sleep quality, and lower disease risk. Approaches to maintaining a healthy circadian rhythm and improving aging health include:

1. Set times. Eating meals at consistent times each day;
2. Right energy. Consuming appropriate energy intake;
3. Diet. Ensuring a healthy, well-balanced diet;
4. Sleep. Getting enough, good-quality sleep daily;
5. Exercise. Getting sufficient exercise;
6. Sunlight. Regular exposure to sunlight/daylight (helps decrease mood disorders, increase alertness, and provides access to vitamin D);
7. De-stress. Proper stress management.

Safeguarding our internal clock is key to healthy aging

Ever gone to an older relative’s home or nursing home and felt like you were in a sauna because it is so warm in there? That is because our ability to properly regulate temperature changes as we age. While age affects our ability to regulate temperature, abnormalities in our circadian clock (both in the brain and in various tissues) cause other seemingly, age-related alterations. While more investigation is required to determine how to age optimally with a healthy circadian clock. Preserving our circadian rhythms may help us live longer and age more gracefully.