The Reticular Activating System (RAS): The Gatekeeper of Awareness

11-05-2025

By Dr. Howard Friedman, M.D. | Veteran | U.S. Army Medical Corps | Internal Medicine | HHOM LLC

In the quiet between breath and thought, the reticular activating system decides what becomes our reality.

Poem — Gatekeeper

Before sight becomes seeing,

before sound becomes meaning,

something deep in the brain

opens its narrow gate.

A million signals knock,

but only a few are chosen—

the cry of a child,

the whisper of danger,

the memory of someone we love.

Call it awareness,

call it survival,

call it the ancient sentinel

that decides what enters our life.

It does not ask if we are ready—

it simply lets us feel

what it believes we must.

—Dr. Howard Friedman, M.D.

Introduction — The Brain’s Hidden Gatekeeper

We like to believe we experience the world exactly as it is—that we see everything, hear everything, and then make sense of it. But long before awareness reaches the mind, the reticular activating system (RAS)—a primitive network deep in the brainstem—filters reality. It decides what is allowed into consciousness. Long before awareness reaches the mind, there is a filter, a sentinel nestled deep in the brainstem, deciding what we’re allowed to notice. It’s called the reticular activating system, or RAS. Every second, our senses collect millions of pieces of information. If all of it entered our awareness, we would drown in sensation. So the RAS stands guard. It asks: Is this safe? Is this familiar? Is this important? Only then does it send certain signals upward to the conscious brain.

Reality is not everything that exists. It is only what the gatekeeper allows through.

I. We Think We’re in Charge — But the Body Moves First

Most of us live with the quiet illusion that we control our feelings and perceptions. But biology tells a humbler truth: the body decides before the mind understands.

Awareness does not begin in thought. It begins in the autonomic nervous system — in the brainstem — where survival lives.

The RAS is the first to respond. It chooses which signals reach awareness. Then the autonomic nervous system responds:

• Sympathetic system — prepares for danger (fight, freeze, flight).

• Parasympathetic system — restores calm (rest, repair, digest).

Only after this does the thinking brain — the cortex — arrive and write a story about what “we decided.”

This isn’t weakness. It’s design.It kept our ancestors alive.The problem is when the gatekeeper never stands down.

II. What Exactly Is the Reticular Activating System?

The RAS is a network of neurons in the brainstem (pons, medulla, midbrain), projecting to the thalamus and cerebral cortex. It controls:

1. Wakefulness and sleep If the RAS is active — we are awake. If it shuts down — coma or unconsciousness.

2. Sensory filtering Our senses detect everything. The RAS chooses what reaches awareness and what disappears.

3. Priority of attention It constantly asks: Does this matter? Examples:

• Hearing your name in a noisy room.

• A mother waking to a faint cry.

• The “blue car” effect after you decide to buy one.

What we notice is not random — it is filtered.

III. When the Gatekeeper Won’t Stand Down — Trauma, Veterans, and Hypervigilance

In combat or trauma, the RAS learns to prioritize survival above all else. It becomes overtrained, always alert.

What saved a soldier’s life in war becomes disruptive at home.

Common signs of a hyperactive RAS:

• Hypervigilance — constantly scanning exits, back to the wall.

• Startle responses to sound or touch.

• Insomnia or light sleep.

• Sensory overload — conversations, traffic, TV all at once.

• Emotional exhaustion and irritability.

These aren’t character flaws. They’re the physiology of survival.

Veterans often say: “I know I’m safe, but my body doesn’t believe me.” This isn’t weakness — it’s wiring.And wiring can change.

IV. Retraining the Gatekeeper — How We Quiet the RAS

The RAS learns through repetition, emotion, and attention. Trauma teaches it danger. Healing teaches it life.

1. Gratitude — Biology, Not Just Philosophy

Gratitude activates the prefrontal cortex and parasympathetic system. It lowers cortisol. It tells the RAS: “You can stop scanning for threats — there is something good here.”

2. Breath — The Parasympathetic Override

Slow diaphragmatic breathing (especially longer exhales) activates the vagus nerve. It sends a direct message to the brainstem: “We are not in danger.”

3. Intention and Attention — Teaching the RAS What to See

The RAS is obedient. What we repeatedly focus on becomes what it looks for — danger or beauty, threat or meaning.

4. Meditation — Training the RAS Not to React to Every Signal

Meditation teaches the brain to notice without reacting. The RAS learns that not every sound, thought, or memory is an emergency.

5. Rituals of Safety and Rhythm

Consistency calms the RAS.Sleep routines. Morning rituals. Quiet spaces. Predictability tells the nervous system: “This is home, not battle.”

6. When Help Is Needed

Some systems are overloaded. Therapy (EMDR, somatic work, CBT), biofeedback, medication — these help the brain and RAS reset. This is not weakness. It is care.

V. The Medicine of Awareness and Purpose

The RAS is not only a filter for danger — it is a filter for meaning. It asks: “Does this matter to you?”

When a person has no purpose, the RAS shrinks their world to survival. But purpose — love, service, creativity, faith — widens the lens. It gives the body a reason to stand down.

Purpose does not erase trauma. It tells the nervous system: “There is still something worth waking up for.”

VI. Closing Reflection and Poem

We may not fully control what we feel, but we are not powerless. We can teach the gatekeeper to see more than threat. Sometimes healing begins with simply noticing what is already here.

Poem — When the Gatekeeper Rests

When the world quiets

and the breath finally reaches the bottom of the lungs,

the gatekeeper loosens its hold.

No longer scanning the horizon

for what might go wrong,

it notices instead—

the warmth of a cup in the hand,

the weight of a heartbeat,

the way light settles on the floor.

This is not forgetting the past.

This is returning to the present.

A truce between body and mind,

between vigilance and trust.

Not everything is danger.

Not every signal is a call to arms.

Some things are simply life

—arriving, quietly, asking to be felt.

—Dr. Howard Friedman, M.D.

—Dr. Howard Friedman, M.D.

Board-Certified | Internal Medicine | Veteran | U.S. Army Medical Corps

Founder of Howard’s House of Medicine (HHOM LLC)

https://www.hhomllc.com

Frequently Asked Questions:

Q: If awareness begins in the body, do we really have free will?

A: Not in the way we’ve been taught. The RAS and autonomic nervous system respond before the conscious mind. Your body feels, reacts, and protects you long before you form a thought about it. Free will doesn’t disappear—it just happens later. It’s not in the first reaction; it’s in the second. It lives in the pause after the emotion—when you choose how to respond, how to breathe, what to believe. Awareness gives you that pause. Healing isn’t about erasing the body’s instincts; it’s about teaching them you’re safe now.

Q: Can trauma permanently damage the RAS, or can it be retrained?

A: The RAS is not broken in trauma—it is overtrained to protect. It becomes a soldier who never gets the order that the war is over. That’s why veterans scan exits in restaurants, hear danger in silence, and wake at the slightest sound. The good news? The RAS is teachable. Through breath, gratitude, therapy, predictability, ritual, safe human connection, and purpose—it learns new rules. It doesn’t forget danger, but it learns to trust peace. Neuroplasticity means survival wiring can become living wiring again.

Q: Why does the RAS notice pain and threat more easily than beauty or peace?

A: Because its first job is survival, not happiness. Evolution wired the RAS to see the tiger in the grass—not the sunrise behind it. It highlights pain, conflict, insults, danger—because those could kill us. Beauty doesn’t. That’s why gratitude, meditation, prayer, and purpose aren’t just “nice ideas”—they are neurological training. They tell the RAS, again and again: look here, this matters too. Over time, the gatekeeper shifts. The world doesn’t change—but what enters you does.