Cortisol often gets labeled as a “stress hormone,” but in a healthy body, cortisol is not the enemy. It’s a guiding hormone. One that helps regulate energy, blood sugar, inflammation, blood pressure, and the sleep–wake cycle.

When cortisol follows its natural daily rhythm, mornings feel alert, energy stays steady, and sleep becomes deep and restorative. When the rhythm is disrupted, the body can feel wired at the wrong times and tired when energy is needed.

The good news is that cortisol rhythm responds quickly to daily habits—how you eat, sleep, move, manage stress, and expose yourself to light. Small, consistent changes can help bring this rhythm back into balance.

Understanding the Natural Cortisol Rhythm

Cortisol is produced by the adrenal glands and coordinated by the brain through the hypothalamic–pituitary–adrenal (HPA) axis.

In a healthy pattern:

• Cortisol rises in the early morning, helping you wake up, focus, and mobilize energy.
• It gradually declines throughout the day, allowing the nervous system to relax and unwind. 
• Cortisol remains low in the evening so melatonin can rise and support sleep.

This rhythm is coordinated by the brain’s master clock—the suprachiasmatic nucleus (SCN)—which responds to light, meal timing, and nervous system signals. When these cues are out of sync, timing often becomes the problem, not necessarily the total amount of cortisol being produced.

When cortisol rises and falls appropriately throughout the day, it supports mental clarity, stable metabolism, immune regulation, and emotional resilience.

When Cortisol Runs Too High or Too Low

Cortisol balance is not always about “too much” or “too little” across the board. It’s also about timing.

Some people experience cortisol that stays elevated into the evening, making it harder to wind down. Others experience cortisol that doesn’t rise adequately in the morning, leading to fatigue, inflammation, weight changes, and difficulty sleeping later on.

Both patterns benefit from the same foundational approach. Stable blood sugar, reduced inflammatory load, nutrient sufficiency, and a predictable rhythm help to balance cortisol over time. In practice, most imbalances reflect disrupted timing rather than true over- or under-production, meaning the body is responding protectively to signals it perceives as mismatched or unsafe.

For example, elevated evening or nighttime cortisol may occur when inflammation is high from immune-triggering foods, when blood sugar drops too low during the evening or night and cortisol rises to restore glucose as a safety mechanism, or when ongoing emotional or relational stress keeps the nervous system on alert.

How Nourishment Supports Cortisol Balance

Morning: Supporting the Natural Rise

In the morning, cortisol is already doing important work—supporting alertness, freeing fatty acids for energy, and helping the brain engage.

Starting the day with protein, healthy fats, and fiber works with this rhythm by:

• Supporting steady blood sugar
• Preventing midmorning crashes
• Reducing the need for reactive stress hormones later

Evening: Supporting the Natural Fall

In the evening, the goal is quite different. The body benefits from cues that say “fuel is available, safety is present, repair can begin.”

Including slow-digesting complex carbohydrates with dinner—such as sweet potatoes, winter squash, lentils, quinoa, carrots, or brown rice—can help support this transition. For individuals with reduced insulin sensitivity or prediabetes, portion size matters. Larger or frequent carbohydrate loads may keep blood sugar elevated into the evening, which can interfere with restorative sleep. In these cases, a smaller amount—roughly ¼ to ½ cup total of complex carbohydrates—may be more supportive.

When evening nourishment is well matched to the body’s needs, it helps to:

• Maintain stable blood sugar overnight
• Keep cortisol low through the night
• Support the natural rise of melatonin

When evening nourishment is insufficient—whether from too few calories overall or too little carbohydrate—the body may rely on cortisol to mobilize stored glycogen from the liver in order to keep blood sugar stable. This protective response can interrupt sleep and create nighttime wakefulness. 

Because blood sugar and cortisol are tightly interconnected, steady fuel in the evening directly supports a smoother nighttime hormonal rhythm:

• When blood sugar remains steady, cortisol can follow its natural curve.
• When glucose dips too low overnight, cortisol may rise to correct it, nudging the body awake.
• When evening nourishment is balanced, sleep deepens naturally and uninterrupted rest becomes more accessible.

Why carbs at dinner can support melatonin

• Melatonin is made from tryptophan
• Tryptophan must cross the blood–brain barrier
• A small amount of carbohydrate triggers insulin
• Insulin helps clear competing amino acids from circulation
• This allows tryptophan to enter the brain more easily
• Once in the brain, tryptophan is converted into serotonin and then melatonin

Fiber-rich complex carbohydrates also slow glucose absorption while delivering B vitamins, antioxidants, and anti-inflammatory phytochemicals. These nutrients actively support nervous-system calm and deeper, uninterrupted rest.

It’s important to note that these benefits come from a small, steady rise in insulin created by a modest amount of fiber-rich complex carbohydrates. This signal helps tryptophan enter the brain, where it can be converted into serotonin and then melatonin.

In contrast, large or repeated insulin spikes, especially from sugary or refined foods, can suppress melatonin and delay its natural evening rise.

Light, Environment, and Hormonal Timing

Cortisol and melatonin respond closely to light cues.

Supportive practices include:

• Bright natural light in the morning
• Warm, low-light environments in the evening
• Light bulbs under 2700 kelvin at night (warm light)
• Firelight or candlelight to encourage melatonin production

High-resolution human studies show that nighttime light exposure suppresses melatonin within minutes and can alter cortisol signaling depending on timing, intensity, and duration. Even intermittent light at night changes hormonal coordination, reinforcing how sensitive the nervous–endocrine system is to evening light cues.

Darkness supports melatonin. Melatonin supports repair, immune balance, detoxification, and brain cleansing through the glymphatic system.

Inflammation, the Gut, and Cortisol Balance

Inflammation can strongly influence cortisol rhythm. When inflammatory cytokines such as IL-6, TNF-α, and IL-1β rise—whether from food sensitivities, gut irritation, metabolic stress, or chronic health conditions—they can activate the immune system and signal the brain to ramp up the HPA axis. Because cortisol is one of the body’s main anti-inflammatory hormones, the brain may increase cortisol at biologically inconvenient times, including the evening or overnight. This can lead to a blunted morning rise, higher nighttime cortisol, and more nighttime waking. However, not everyone responds the same way. Some people develop overall low cortisol or reduced cortisol sensitivity instead. 

Chronic low-grade inflammation can also signal the brain that the body is unsafe, keeping the stress response active and making it harder for cortisol to drop in the evening.

Addressing inflammation at its root, by reducing immune-triggering foods, supporting gut health, and improving detoxification can lower inflammatory signaling and help cortisol regulate more normally. Improved cortisol signaling supports downstream systems like sleep, mood, metabolism and weight, and overall resilience. This is why food and gut support are foundational for restoring balance.

Supportive steps include:

• Reduce foods that trigger inflammation through a well-planned elimination diet
• Support a diverse, well-nourished gut microbiome
• Include anti-inflammatory foods and herbs rich in polyphenols
• Ingredients like turmeric, ginger, green tea, berries, grape skins, and brightly colored vegetables help modulate inflammatory pathways and support calmer cortisol signaling

→ Download my guide: How to Do an Anti-Inflammatory Diet.

Alongside food, the vagus nerve plays a powerful role in regulating inflammatory signaling. As the body’s main parasympathetic pathway, it sends “all is well” signals that help reduce excess inflammatory cytokines and support healthy HPA-axis regulation. Simple practices such as slow breathing with a long exhale, gentle humming, sipping warm tea, mindful eating, and spending time in safe, attuned relationships all support this calming pathway. When the nervous system feels anchored—both internally and relationally—cortisol can return to a calmer, more natural rhythm.

Nutrients That Support Adrenal Function

A well-regulated stress response depends on steady, foundational nourishment. Certain nutrients help the adrenal system stay supplied, responsive, and resilient throughout daily demands.

Key nutrients include:

• Vitamin C, which is highly concentrated in the adrenal glands and used during cortisol production
• Amino acids, which provide building blocks for neurotransmitters and support metabolic balance
• Magnesium and B vitamins, which calm neural excitability, support energy production, and help the nervous system adapt smoothly to stress
• Omega-3 fatty acids, which help modulate inflammation, support cell signaling, and reduce overall stress load on the HPA axis

During chronic stress or inflammation, the body consumes these nutrients at a faster rate to support hormone synthesis, antioxidant defense, and nervous system repair, raising baseline needs even when intake appears sufficient.

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Pulling It All Together: Nourishing Cortisol Balance

Balancing cortisol is about restoring rhythm and responsiveness. When the body feels supported, cortisol rises naturally when it’s needed—to promote alertness, focus, and energy—and falls smoothly when its work is done, creating space for rest, repair, and deep sleep to unfold.

When cortisol falls smoothly in the evening, melatonin is free to rise during its natural overnight window, supporting immune repair, antioxidant activity, and neurological restoration.

From a nourishment perspective, that rhythm is built gradually through consistency:

• Protein, fat, and fiber at breakfast provide steady fuel and work with the natural morning cortisol rise.
• Balanced meals throughout the day prevent reactive cortisol shifts.
• Complex carbohydrates at dinner support stable nighttime blood sugar and melatonin production.
• Consistent nourishment—not excess or scarcity—signals safety to the nervous system.
• Reducing inflammatory triggers, supporting detoxification, restoring nutrients, healing the gut, and protecting sleep all reinforce this rhythm.

Everything we’ve explored in the first ten months of The 12 Gifts of Health works together to bring cortisol back into balance.

For a deeper exploration of cortisol rhythm, daily practices, and supportive nourishment, visit Gift #11: Restore Balance by Regulating Cortisol.

And What Comes Next…

As powerful as food and nutrients are, there is one influence that can recalibrate cortisol more deeply than almost anything else...

Safety within connection.

Supportive, attuned relationships calm the nervous system and soften the stress response, signaling—at a biological level—that the body can shift out of persistent alertness. Experiences of safety, whether through nourishment, rhythm, or healthy connection, allow cortisol regulation to become more efficient over time.

That’s where we’re headed next.

Month 12: Healthy Relationships explores how connection, attunement, emotional safety, boundaries, and consistent self-care complete the healing loop, allowing the body to finally step out of survival mode and into sustained balance.

References:

Kelly, M. J., Breathnach, C., Tracey, K. J., & Donnelly, S. C. (2022). Manipulation of the inflammatory reflex as a therapeutic strategy. Cell reports. Medicine, 3(7), 100696. https://doi.org/10.1016/j.xcrm.2022.100696 

Nunez, S. G., Rabelo, S. P., Subotic, N., Caruso, J. W., & Knezevic, N. N. (2025). Chronic Stress and Autoimmunity: The Role of HPA Axis and Cortisol Dysregulation. International journal of molecular sciences, 26(20), 9994. https://doi.org/10.3390/ijms26209994

Pachimsawat, P., Ratanachamnong, P., & Jantaratnotai, N. (2024). Exogenous melatonin's effect on salivary cortisol and amylase: A randomized controlled trial. Pharmacology research & perspectives, 12(3), e1205. https://doi.org/10.1002/prp2.1205

Porges, S. W. (2022). Polyvagal theory: A science of safety. Frontiers in Integrative Neuroscience, 16, Article 871227. https://doi.org/10.3389/fnint.2022.871227

Rahman, S. A., Wright, K. P., Jr, Lockley, S. W., Czeisler, C. A., & Gronfier, C. (2019). Characterizing the temporal Dynamics of Melatonin and Cortisol Changes in Response to Nocturnal Light Exposure. Scientific reports, 9(1), 19720. https://doi.org/10.1038/s41598-019-54806-7

Wright, K. P., Jr, Drake, A. L., Frey, D. J., Fleshner, M., Desouza, C. A., Gronfier, C., & Czeisler, C. A. (2015). Influence of sleep deprivation and circadian misalignment on cortisol, inflammatory markers, and cytokine balance. Brain, behavior, and immunity, 47, 24–34. https://doi.org/10.1016/j.bbi.2015.01.004