Cortisol vs. melatonin: Our body’s sun and moon

Created on: July 19, 2021

Picture this: you wake up from a deep sleep feeling refreshed, rejuvenated, and ready to take on your day. Your eyes spring open effortlessly without an alarm before you plunge enthusiastically into a full, productive day with no morning grogginess and no need for coffee.

If you think this scenario sounds far-fetched, you definitely aren’t alone!

The truth is, your quality of sleep, how you feel when waking, and your resilience to stress through the day will all largely come down to the balance between two very important and closely related hormones: melatonin and cortisol.

Chemical messengers: How hormones help us sleep

What is melatonin and what does it do?

Melatonin is found not just in humans but also in animals, plants, fungi, and bacteria. This molecule has remained completely unchanged for over 3 billion years. Fascinatingly, melatonin is made and used all over the body in cells of the brain, the gut, and the immune system. Beyond regulating sleep, melatonin is an anti-inflammatory, an immunomodulator, an antiviral, a brain detoxifier, a gut tonic, a mitochondrial defender, and an extremely potent antioxidant!

Sleep drive and your body’s natural clock

When the eyes are exposed to darkness, a biochemical cascade is set into motion to prepare the body for sleep. Electrical signals from the retina travel to a region of the brain called the suprachiasmatic nucleus that acts as an internal clock, signaling the pineal gland to produce melatonin to induce and sustain sleep.

What is cortisol and what does it do?

Cortisol, the stress hormone, is also known as the ‘fight-or-flight’ hormone. When the hypothalamus in our brain perceives a stressful event or situation, it sends a signal to the pituitary gland which then relays a signal to the adrenal cortex to produce cortisol.

Since the earliest days of human prehistory, cortisol as a key survival hormone has had a central role in helping us defend ourselves against danger, or run away from it as the case may be.

Cortisol helps us to:

  • Extend the halflife of adrenaline
  • Raise blood pressure
  • Speed up breathing and heart rate
  • Slow digestion

In these modern times, we are more likely to face a stressful deadline at work than a natural predator threatening to eat us. However, on a physiological level, the instruction from the brain to the adrenal glands is the same: secrete cortisol to help us survive.

The wakey-wakey hormone

On top of helping us confront the stressors of life, cortisol is responsible for waking us up in the morning – it’s the “up and at ‘em” hormone! After pulling us from our slumber, cortisol peaks in the blood within 45 minutes of waking and slowly declines over the course of the day. This is assuming, of course, that no stressful surprises cause it to spike.

How cortisol and melatonin work in opposition

Sleep and circadian rhythm

Melatonin comes out when darkness falls to promote deep, restful sleep. Cortisol, melatonin’s natural opposite, comes out with the sun to wake us up and power us through the morning.

At the end of the day when the sun sets, cortisol declines again, handing the reins back over to melatonin. This natural process, alternating melatonin and cortisol over a 24-hour sleep-wake cycle, is known as the circadian rhythm, and it keeps us synchronized with the night and day.

Circadian disruption

If you have ever experienced jet lag, you have experienced a disrupted circadian rhythm: you’re wide awake when all you want to do is sleep, or you’re tired when you want to feel alert.

Insomnia, or waking up in the middle of the night, can also reveal an imbalance in the melatonin-cortisol system.

Chronic stress takes a toll

Our endocrine system is tightly interconnected, and the production of cortisol is always given priority since survival is always of utmost importance. Chronically elevated levels of cortisol can lead to various other hormonal imbalances affecting testosterone, estrogen, the ‘fountain of youth’ hormone DHEA, and more.

Compromised immunity is also a well-known consequence of a cortisol imbalance, and severely stressed-out people, as well as those suffering from sleep deprivation, or working irregular shifts, are at a generally higher risk of sickness and infection.

Achieving a healthy balance of these hormones


Maintain blood sugar balance. Cortisol is also used by the body for gluconeogenesis, creating new sources of cellular fuel when blood sugar rides low. This is why a snack before bed can actually sometimes be helpful in preventing nighttime wakefulness!

Avoid known allergens, especially at dinner, as these internal stressors can elicit a cortisol response.

Eat melatonin, serotonin, or tryptophan-rich foods like tart cherries, kiwis, or goji berries before bed.

Lifestyle habits

Early morning sunlight helps with cortisol production, but sunlight during the day also helps with melatonin balance by raising serotonin, which will later be converted to melatonin when the sun goes down.

Speaking of which, it is very important to avoid light in the 2 or 3 hours leading up to bedtime, as darkness before bed is the single most important factor in encouraging healthy melatonin production. And get to bed early! The hours before midnight are particularly rejuvenating for the adrenals.

Finally, supplemental melatonin can be a game-changer in getting that much-needed rest while putting the sleep-wake cycle back on track.


Melatonin: an ancient molecule that makes oxygen metabolically tolerable

Effect of melatonin supplementation on sleep quality: a systematic review and meta-analysis of randomized controlled trials

Anti-inflammatory effects of melatonin: A systematic review and meta-analysis of clinical trials

Melatonin potentials against viral infections including COVID-19: Current evidence and new findings

Non-vertebrate melatonin

Melatonin: Clinical Perspectives in Neurodegeneration

The Human Suprachiasmatic Nucleus

Effect of tart cherry juice (Prunus cerasus) on melatonin levels and enhanced sleep quality

Effect of kiwifruit consumption on sleep quality in adults with sleep problems

A randomized, double-blind, placebo-controlled, clinical study of the general effects of a standardized Lycium barbarum (Goji) Juice, GoChi