Cortisol, Breathing, and Sleep: The Missing Link to Your Health

By Jason KauffmanFebruary 12, 2025

Introduction: Why You’re Exhausted, Stressed, and Can’t Seem to Fix It

You wake up groggy, even after what should have been a full night’s sleep. Your energy crashes by mid-afternoon, and by evening, your mind is racing while your body feels drained. Despite trying supplements, better nutrition, and exercise, something still feels off. Maybe your doctor suggested stress as the culprit, pointing to elevated cortisol levels, the infamous stress hormone. But why does it feel like no matter what you do, you can’t fully recover?

What if the problem isn’t just stress—but how you breathe and sleep?

It might surprise you, but breathing through your mouth at night could be quietly sabotaging your health, keeping your body in a state of stress, and disrupting the natural cortisol cycle. Chronic mouth breathing prevents deep, restorative sleep, keeping cortisol levels unnaturally high. And when cortisol is out of balance, everything else—your metabolism, immune system, mood, and energy levels—suffers.

The solution isn’t found in another supplement or biohack. The first step to lowering stress and restoring energy is fixing your breathing and sleep quality. That’s where nasal breathing and mouth tape come in—a simple, natural way to get your body back on track.

Cortisol: The Hormone That Controls More Than Just Stress

Cortisol is often misunderstood. While it’s labeled the stress hormone, it’s actually a vital regulatory hormone that affects nearly every system in the body. It’s produced by the adrenal glands and plays a role in:

Regulating metabolism by helping convert food into usable energy
Managing blood sugar to prevent dangerous highs and lows
Controlling blood pressure and cardiovascular function
Reducing inflammation to help the immune system fight infections
Influencing mood, memory, and brain function

Cortisol naturally follows a rhythm throughout the day. In a healthy individual, cortisol is highest in the morning, helping you wake up feeling alert. It gradually declines through the day, reaching its lowest levels at night so the body can transition into deep, restorative sleep. This natural cycle is called the cortisol awakening response (CAR) and is essential for energy regulation.

However, modern lifestyles have disrupted this rhythm. Chronic stress, poor diet, artificial light exposure, and most importantly—disordered breathing—keep cortisol levels high at the wrong times, preventing proper recovery.

Sleep, Cortisol, and the Role of Breathing

Good sleep isn’t just about getting enough hours—it’s about cycling through the deep and REM sleep stages that allow the body to reset cortisol levels. But poor breathing habits, particularly mouth breathing, can disrupt this cycle entirely.

Mouth breathing signals to the body that it's in fight-or-flight mode, triggering the sympathetic nervous system (SNS). Instead of deep, restful sleep, the body remains in a low-grade stress state, leading to:

Frequent nighttime awakenings
Shallow, unrefreshing sleep
Increased snoring and sleep apnea episodes
Elevated morning cortisol levels
Chronic fatigue and brain fog

A 2016 study in the Journal of Clinical Endocrinology & Metabolism found that individuals with poor sleep quality had consistently higher cortisol levels, particularly in the evening, making it harder to fall and stay asleep. Another study in Sleep Medicine Reviews (2018) highlighted that mouth breathing and obstructed nasal airways contributed to sleep fragmentation, higher nighttime heart rates, and disrupted hormonal balance—a direct recipe for cortisol dysregulation.

If you’re waking up groggy, restless, or feeling stressed before your feet even hit the floor, your breathing habits at night may be to blame.

Why Mouth Breathing Wrecks Your Sleep and Health

Breathing through the mouth instead of the nose at night isn’t just a bad habit—it’s a biological stressor. The body isn’t designed for mouth breathing; it’s a survival mechanism meant for emergencies. When we breathe through our mouths for prolonged periods, it leads to chronic low-grade hyperventilation, which has several negative effects:

Lower Oxygen Absorption: Mouth breathing bypasses the nasal passages, reducing nitric oxide (NO) production. Nitric oxide is crucial for oxygen efficiency, immune function, and blood vessel dilation. Without it, cells receive less oxygen, triggering stress signals in the brain.
Higher Cortisol & Increased Heart Rate: Mouth breathing increases the respiratory rate, causing CO₂ levels to drop too quickly. Low CO₂ forces the body to compensate by increasing cortisol and activating the fight-or-flight response, keeping your nervous system in stress mode all night.
Snoring and Sleep Apnea: A study in Chest Journal (2019) confirmed that mouth breathers are far more likely to suffer from obstructive sleep apnea (OSA), a condition where breathing stops multiple times per hour, leading to oxygen deprivation and micro-awakenings.
Dehydration and Inflammation: Mouth breathing dries out the throat and nasal passages, increasing the risk of chronic inflammation, allergies, and respiratory infections.

Over time, these issues compound, making it harder for the body to regulate cortisol levels, recover from stress, and function optimally.

The Natural Solution: Mouth Tape and Nasal Breathing

The fastest, simplest way to restore proper breathing at night is using mouth tape to encourage nasal breathing. By gently sealing the lips, Lunasol Sleep Mouth Tape naturally trains the body to breathe through the nose, promoting relaxation and deep sleep.

How Mouth Tape Helps:

Encourages diaphragmatic breathing, reducing stress signals in the brain
Supports nitric oxide production, improving oxygenation and blood flow
Prevents snoring and airway collapse, reducing the risk of sleep apnea
Lowers nighttime cortisol levels, allowing proper sleep cycle regulation
Improves deep and REM sleep, leading to better energy and mood upon waking

A 2020 study in Respiratory Physiology & Neurobiology showed that individuals who practiced nasal breathing had lower nighttime cortisol and better heart rate variability (HRV), indicating reduced stress levels.

Lunasol Sleep Mouth Tape: A Comfortable and Effective Option

Lunasol Sleep offers three styles of medical-grade, hypoallergenic mouth tape, ensuring a comfortable fit for all skin types and even beards:

Barely There – A minimal design for those new to mouth taping
Just the Lips – Covers only the lips, providing gentle but effective support
Fully Covered – Maximum coverage for those needing complete reinforcement

Made from safe, medical-grade adhesives, Lunasol Sleep Mouth Tape allows for easy removal and breathable support, making nasal breathing an effortless nighttime habit.

Final Thoughts: Fix Sleep and Breathing First

If you’ve been struggling with high cortisol, stress, and poor sleep, don’t rush to band-aid solutions like supplements or stimulants. Fix the foundation first—your breathing and sleep quality.

By switching to nasal breathing with the help of mouth tape, you can: