Circadian Biorhythm and Diabetes

Circadian Biorhythm and Diabetes

What is Circadian Biorhythm?

The circadian rhythm is your body’s natural 24-hour clock that controls your sleep-wake cycle and other important functions, like hormone levels, metabolism, and body repair. It is guided by a part of the brain called the suprachiasmatic nucleus in the hypothalamus.

This clock works in sync with the Earth’s day and night cycle and is influenced by daily habits like sunlight exposure, eating times, and physical activity. A well-regulated circadian biorhythm ensures optimal hormonal and metabolic function, promoting physical and mental health. Conversely, disruption of this rhythm can lead to health complications, including metabolic disorders like diabetes mellitus. Understanding and managing circadian rhythms is, therefore, crucial in preventing and treating such conditions.

Sequence of Circadian Biorhythm

The human circadian biorhythm operates in a highly organized sequence that aligns with daily environmental changes.

Key events in our body happen at specific times:

Morning (6 AM – 12 PM):

Cortisol hormone peaks around 7–8 AM to help us wake up, feel energetic, and stay alert.

Ghrelin, the hunger hormone, rises, making us feel hungry after fasting overnight. Our body is most sensitive to insulin, helping us process food better, especially at breakfast and lunch.

Afternoon (12 PM – 6 PM):

Energy stays steady but starts to drop as the day goes on.

Digestive hormones help process food during lunch.

Cortisol starts to decrease, while serotonin (the mood and focus hormone) increases.

Evening (6 PM – 10 PM):

As it gets darker, the body starts to produce melatonin, which helps us wind down for sleep.

Leptin, a hormone that reduces hunger, rises to stop us from snacking too much at night.

Night (10 PM – 6 AM):

Growth hormone increases during deep sleep, helping repair tissues and regenerate cells.

Melatonin peaks, helping us sleep better and providing antioxidant benefits.

Cortisol levels drop, allowing us to sleep peacefully.

This precise rhythm maintains metabolic homeostasis.

However, irregular sleep patterns, night shifts, and late-night eating can disrupt this sequence, leading to hormonal imbalances.

Abnormal Circadian Biorhythm in Diabetes

Disruption of circadian rhythms is one of the major contributors to the development and progression of Type 2 Diabetes mellitus.

Here’s how circadian misalignment impacts diabetes:

Insulin Resistance:

Normally, insulin sensitivity is highest in the morning and decreases later in the day. Circadian disruption reduces insulin’s effectiveness, leading to poor glucose uptake and elevated blood sugar levels.

Dysregulated Cortisol Levels:

Chronic circadian misalignment causes cortisol to peak at inappropriate times (e.g., at night), which can worsen glucose intolerance and increase the risk of hyperglycemia.

Melatonin Suppression:

Poor sleep or exposure to artificial light at night reduces melatonin levels, impairing pancreatic beta-cell function and insulin secretion.

Imbalanced Appetite Hormones:

Sleep deprivation decreases leptin (satiety hormone) and increases ghrelin (hunger hormone), leading to overeating, especially carbohydrate-rich foods. This contributes to weight gain and exacerbates insulin resistance.

Evidence: Studies have shown that shift workers are at a significantly higher risk of developing Type 2 Diabetes Mellitus due to disrupted circadian rhythms. Additionally, irregular sleep patterns worsen glycemic control in patients with diabetes.