The Hormone Orchestra
Our bodies run on an internal 24-hour clock that carefully times the release of key hormones like melatonin, cortisol, insulin, growth hormone, leptin, ghrelin, and many more. When this clock is in sync, these hormones rise and fall throughout the day in harmony, keeping our energy, mood, metabolism, appetite, and recovery in balance. But when the rhythm is disrupted, that balance starts to break down, and we begin to feel the effects of that dysregulation in our bodies. Let’s take a look at how this clock works, so you can better recognize when it’s out of sync.
Melatonin: The Nighttime Signal
Melatonin is often called the hormone of darkness, and for good reason. As the sun sets and light fades, your brain starts releasing melatonin, and a cascade of critical events occurs. Melatonin stays low during the day and rises in the evening, peaking in the early hours of the morning¹.
Cortisol: Nature’s Alarm Clock
If melatonin is your sleep switch, cortisol helps wake you up. It follows the opposite rhythm, lowest at night and peaking within 30–45 minutes of waking. This spike, called the Cortisol Awakening Response, helps you feel alert, stabilize your blood pressure, and raise your blood sugar for morning energy².
In circadian misalignment, cortisol rhythms flatten or shift. Studies in shift workers have found a blunted morning cortisol rise and higher-than-normal cortisol levels at night, bad news for both energy and sleep³. Long-term, a disrupted cortisol pattern is associated with increased stress, lower mood, and immune suppression.
Insulin: The Daytime Energy Manager
Unlike melatonin and cortisol, insulin isn’t on a strict schedule. Instead, it gets released when you eat. But your sensitivity to insulin does follow a rhythm, making you more efficient at processing carbs earlier in the day⁴.
Late-night eating is problematic because insulin sensitivity is lower in the evening. In one study, people who ate most of their calories at night had higher blood sugar and worse insulin responses, even when total intake was the same⁵. Shift workers, who often eat at biologically inappropriate times, have consistently shown higher rates of insulin resistance and metabolic syndrome⁶.
Growth Hormone: The Overnight Repair Crew
Growth hormone (GH) supports tissue repair, muscle growth, and fat metabolism. It’s released in pulses during deep sleep, mostly in the first few hours of the night. It. Your circadian rhythm plays a big role here⁷. When sleep is disrupted or mistimed, growth hormone levels drop. In people with fragmented sleep, GH levels are significantly lower than in normal sleepers, which can impair recovery, increase fat storage, and reduce lean muscle⁸.
Leptin and Ghrelin: Appetite’s Yin and Yang
Leptin and ghrelin work together to help regulate hunger and fullness. Leptin, which is produced by fat cells, signals fullness. Ghrelin, produced by the stomach, signals hunger. These hormones work in tandem and naturally follow a rhythm: ghrelin rises before meals, while leptin peaks at night to suppress appetite while you sleep⁹.
When your circadian clock is mistimed, these rhythms get disrupted. Research shows that poor sleep lowers leptin and raises ghrelin, which makes you feel hungrier and crave high-calorie foods¹⁰. This is one of the reasons poor Circadian Health is linked to weight gain.
When the Clock Breaks
When your hormonal rhythms are in sync, your body works like a symphony. When they’re misaligned, systems start falling apart. Over time, this can lead to fatigue, mood disorders, weight gain, insulin resistance, and even long-term health risks like cancer³, heart disease, and type 2 diabetes¹¹.
Looking Ahead
The good news? You can restore your rhythm. Getting morning light, eating meals during the day, and sleeping on a regular schedule are important first steps to help reset your hormone clocks.
Your hormones don’t just care how much light, sleep, or food you get. They care when you get them. By learning to live in sync with your internal clock, you may finally start to feel like yourself again.
Dr. Jonathan Moustakis
Co-founder and CTO of Lume Health
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