AMA #7: Cold Exposure, Maximizing REM Sleep & My Next Scientific Studies
The episode, an AMA preview with Dr. Andrew Huberman, discusses whether deliberate cold exposure can cause sickness and its immune effects. It also covers the importance of nasal breathing and avoiding strenuous activities when unwell.
Deep Dive Analysis
8 Topic Outline
Cold Exposure and Sickness Susceptibility
Environmental Factors Affecting Viral and Bacterial Transmission
Guidelines for Deliberate Cold Exposure When Feeling Unwell
Immune System Markers and Deliberate Cold Exposure
Role of Epinephrine and Norepinephrine in Immune Response
Cyclic Hyperventilation and Immune Modulation
Key Takeaways for Cold Exposure and Sickness
Importance of Nasal Breathing for Health
3 Key Concepts
Mucosal Lining
The mucosal lining in your nose and mouth acts as a primary barrier, trapping viruses and bacteria. Spending time in cold, dry environments can thin this lining, making it less robust and potentially increasing susceptibility to infections.
Epinephrine and Norepinephrine
These are molecules (also known as adrenaline and noradrenaline) released in the brain and body in response to stressors like cold water exposure or deliberate hyperventilation. They can temporarily activate immune cells and molecules, enhancing immune function, but chronically elevated levels can reduce immune efficiency.
Sickness Circuits
These are brain circuits activated during viral or bacterial infections that encourage behaviors like resting, moving less, and adopting a fetal position. These behaviors are designed to conserve energy and direct the body's resources towards healing and combating the infection.
4 Questions Answered
Probably not directly from brief (1-10 minute) deliberate cold exposure if you warm up afterwards. However, spending time in cold, dry air, especially if mouth breathing, can thin your mucosal lining and increase susceptibility to viral and bacterial infections.
If you are feeling malaise or very sick, avoid deliberate cold exposure and other stressful challenges like intense exercise or extreme heat. Instead, prioritize rest and warmth. If you are only feeling slightly run down, you can do cold exposure but ensure you warm up thoroughly afterwards.
Repeated deliberate cold exposure can increase immune system markers like T lymphocytes and B lymphocytes, especially when done consistently over time. This effect is partly mediated by the release of epinephrine and norepinephrine, which can trigger the activation of immune cells.
Nasal breathing is generally better than mouth breathing because the nose's mucosal lining is a main barrier against infections. Mouth breathing, particularly in cold, dry environments, can dry out these passages, making them more vulnerable to viruses and bacteria.
9 Actionable Insights
1. Avoid Cold Exposure When Sick
If you are feeling malaise, tired, or significantly unwell due to a cold, flu, or bacterial infection, avoid deliberate cold exposure, strenuous exercise, or heat challenges. Your body needs to conserve resources for healing, and stress from these activities can hinder recovery.
2. Rest When Unwell
When feeling sick, prioritize rest and avoid pushing yourself, as your body’s natural ‘sickness circuits’ are designed to encourage healing. This allows your body to devote all resources to combating the infection.
3. Prioritize Nasal Breathing
Consistently breathe through your nose, unless engaged in strenuous exercise or talking, because it acts as a primary barrier against infections entering through the mouth. Nasal breathing is generally better than mouth breathing for overall health.
4. Gradual Cold Exposure & Warm-up
If new to deliberate cold exposure, start with shorter durations (e.g., 1-3 minutes) and gradually increase, never jumping straight to long exposures like 10 minutes. Always warm up thoroughly afterwards by getting clothed, taking a hot shower/sauna, or basking in the sun to prevent prolonged cold exposure.
5. Warmth for Mild Sickness
If experiencing a mild sniffle or feeling a little run down, opt for warmer hot baths, hot showers, or a non-stressfully hot sauna instead of cold exposure. For mild unwellness, taking a hot shower and going to sleep is often the best advice.
6. Regular Cold Exposure Boosts Immunity
Engage in deliberate cold exposure repeatedly, such as three times per week over six weeks, to potentially increase immune system markers like T lymphocytes and IL-6. This effect is mediated by the release of epinephrine and norepinephrine, which can be pro-immune.
7. Cyclic Hyperventilation for Immunity
Practice cyclic hyperventilation (e.g., Wim Hof breathing, inhaling through the nose and exhaling through the mouth repeatedly 25 times or so) to release norepinephrine and epinephrine. This can activate immune cells and potentially reduce the symptomatic response to infections.
8. Avoid Chronic Adrenaline Spikes
Be mindful that chronically elevated levels of norepinephrine and epinephrine, especially late in the day and sustained over many days, can reduce the number and efficiency of immune cells. This suggests balancing stress-inducing protocols with adequate recovery.
9. Protect Mucosal Lining
Be aware that spending time in cold, dry environments, particularly with mouth breathing, can thin and weaken the mucosal lining of your nose and mouth. This makes you more susceptible to viral and bacterial infections, so protect these areas.
3 Key Quotes
If you're sick, stay out of deliberate cold exposure.
Andrew Huberman
Cold, dry air does seem to increase our susceptibility to viral and bacterial infections because whether or not you're a mouth breather or a nose breather... viruses and bacteria enter through your nose and mouth...
Andrew Huberman
If you are feeling good to great, do your deliberate cold exposure and perhaps don't worry so much about using your body's natural metabolism and thermogenic abilities to heat back up afterwards.
Andrew Huberman