Andrew Huberman on CO2, Breathing, and Brain Function - What It Means for Your Environment

In Summary

• Huberman highlights how CO2 influences breathing drive, blood chemistry, and brain state.
• That internal physiology makes indoor CO2 a practical environmental variable for focus and sleep.
• Framing CO2 as a systems signal, not a fear signal, helps guide better ventilation decisions.

If you've listened to Dr Andrew Huberman's podcast, you've probably heard him talk about carbon dioxide.

Not in a panic-inducing way.

In a physiological way.

Huberman frequently explains how carbon dioxide (CO2) levels in the body influence breathing, oxygen delivery, and brain state. He discusses how changes in CO2 affect respiratory drive and how breathing patterns can shift alertness, calmness, and cognitive performance.

But here's the interesting part.

Most of that conversation focuses on CO2 inside the body.

Very little of the mainstream discussion focuses on CO2 in the room.

And the two are connected.

What Andrew Huberman Says About CO2 and the Brain

In episodes on breathwork and performance, Huberman explains that:

• CO2 levels in the blood influence how strongly we feel the urge to breathe
• CO2 helps regulate blood pH
• Changes in CO2 affect oxygen release from haemoglobin (the Bohr effect)
• Breathing patterns alter CO2 balance, which can influence mental state

In simple terms:

Carbon dioxide is not just a waste gas.

It's part of a regulatory system that influences brain and body function.

When CO2 levels rise in the bloodstream, your breathing adjusts automatically. That adjustment can shift how alert or calm you feel.

That's internal physiology.

Now zoom out.

Indoor CO2 Levels and Cognitive Performance

Outdoor CO2 levels sit around 420 ppm (parts per million).

In enclosed indoor environments - offices, bedrooms, meeting rooms - CO2 can rise above 1,000 ppm, sometimes reaching 1,500 ppm or more in poorly ventilated spaces.

These levels are not dangerous.

But research has explored whether elevated indoor CO2 levels may influence:

• Decision-making performance
• Perceived alertness
• Cognitive speed
• Next-day focus

The science is still evolving. Effects are subtle, not dramatic.

But the mechanism makes sense.

If internal CO2 influences brain state - as Huberman explains - then environmental CO2 becomes a variable worth understanding.

Because indoor air shapes the air you inhale.

And the air you inhale influences the chemistry in your bloodstream.

CO2, Sleep, and Night-Time Ventilation

Huberman has also discussed the importance of breathing patterns during sleep and how respiratory stability influences sleep quality.

What's less commonly discussed is this:

In a closed bedroom overnight, CO2 levels can rise significantly.

You may not notice it.

You don't smell CO2.

But the composition of the air changes.

If CO2 accumulation influences breathing chemistry and respiratory drive, then bedroom ventilation becomes part of the sleep equation.

Not as a fear-based narrative.

As a systems narrative.

Why This Matters for Focus and Performance

Huberman often frames performance as the outcome of:

• Nervous system regulation
• Oxygen delivery
• Breathing patterns
• Environmental inputs

Focus isn't purely psychological.

It's biological.

And biology operates inside physical environments.

Modern buildings are increasingly energy efficient and tightly sealed. That reduces airflow. Reduced airflow can increase indoor CO2 concentration.

The question isn't:

"Is CO2 dangerous?"

At typical indoor levels, it isn't.

The better question is:

"Is ventilation influencing how sharp I feel?"

Expanding the Conversation

The modern health movement has become excellent at measuring internal metrics:

• Heart rate variability
• Sleep staging
• Resting heart rate
• Stress markers

What's still under-measured is the room.

Huberman's discussions about CO2 and breathing highlight how sensitive the brain is to chemical signals.

The emerging frontier is asking:

What role does indoor air quality play in shaping those signals?

Because performance doesn't just happen in the brain.

It happens in an environment.

The Takeaway

Andrew Huberman's work makes one thing clear:

Carbon dioxide is not trivial.

It plays a central role in respiratory chemistry and brain state.

While most of the discussion focuses on internal CO2 and breathwork, indoor CO2 levels are a natural extension of that conversation.

Not as a scare tactic.

As a systems insight.

Sleep and focus are biological.

But they're also environmental.

And the air in the room may be more relevant than we've historically acknowledged.