Cortisol & Melatonin: The Hormones That Regulate Our Body Clock

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Disclaimer: Not medical advice. The following information is for educational purposes only.

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The circadian rhythm is your body’s natural 24-hour clock that tells you when to sleep, wake up, eat, and more → helping your body to function smoothly.

Cortisol

In the morning, when bright light (especially from the sun) enters our eyes, the body releases the cortisol hormone. This acts like a natural stimulant to reduce sleepiness and wake us up. This morning cortisol boost is a critical part of the body’s daily 24-hour reset. After this key circadian event, a cascade of processes within the body are set off throughout the day, following a 24-hour cycle. Cortisol is usually referred to as the “stress hormone”, however during this key time, it’s beneficial.

What happens if we don’t get bright lights in the morning?

Without adequate exposure to bright light in the morning, the body may not trigger a strong cortisol awakening response.

This leads to lower levels of cortisol in the morning, resulting in:

Lower energy levels
Reduced alertness
Negative moods, irritability
Poor memory and concentration
Etc

Melatonin

In the evening, as daylight disappears and darkness sets in, the pineal gland produces and releases melatonin (the sleep hormone). This signals to the brain that it’s time to begin preparing for sleep.

What happens without darkness at night?

At night, many people use electronic screens (TV, mobile, laptop, tablets, etc) and have bright lights overhead. These lights contain a lot of ‘blue light wavelengths’ which suppresses melatonin, signals to the brain it’s daytime and tells our body to stay energized and alert → the opposite of what you want before bed. We evolved living outdoors across millions of years, so our biology is deeply connected to light, the sun, and darkness. When we disrupt these natural processes, our health, mood, and energy suffers. Here’s a clip from Dr. Abud Bakri, explaining why not going outside in the morning, and using artificial lights at night affects our energy levels and mood throughout the day 👇