How to Use Cold & Heat Exposure to Improve Your Health | Dr. Susanna Søberg

Key wellness strategies & practical takeaways (Cold + Heat Exposure)

1) Use deliberate cold to trigger “healthy stress” responses

Cold immersion (e.g., up to the neck) is described as a potent stressor that can activate:

• Sympathetic nervous system (alertness/arousal; increased heart rate)
• Catecholamines: dopamine, epinephrine, norepinephrine
• A cold shock response (often includes hyperventilation/gasping in beginners)

What to aim for (gauge by sensation):

• It should feel uncomfortable enough to produce a cold shock
• Avoid lingering long enough to become dangerously cold/hypothermic

Adaptation matters:

• With repeated exposure, the initial “shock” response often diminishes, meaning you’re building resilience rather than simply white-knuckling discomfort.

2) Don’t confuse discomfort with safety limits

The protocol is intended to be hard but controlled, similar to exercise:

• Discomfort is part of the signal
• But not “extreme enough to be unsafe” (e.g., not to the point of losing normal control / hypothermia)

3) Prefer short, repeated “bouts” over long sessions

A key theme is hormesis via repeated stimulation, not one prolonged exposure.

Proposed dosing targets from the study’s calculations:

• Cold: ~11 minutes/week total deliberate cold exposure (broken across sessions)
• Sauna (heat): ~57 minutes/week total (e.g., ~10–15 min per session)

Practical implication:

• If you do cold, it’s generally better to do multiple short exposures than one long one.
• Keep each bout short enough that you still get a meaningful “stimulus” each time.

4) Consider the “Søberg Principle”: end on cold

Ending on cold after alternating cold/heat is presented as beneficial because it may:

• Force the body to heat itself up naturally
• Support thermogenesis (brown fat + muscle activity)
• Extend effects for hours (not only during the exposure window)
• Fit with sleep regulation logic (core temperature drop is relevant to sleep onset)

5) Combine cold and heat using an “alternating” structure (with caution)

In the winter-swimming protocol described, participants generally did:

• Cold immersion 1–2 minutes
• Then sauna (~80°C) for 10–15 minutes
• Repeat the cycle, typically ending on cold

The emphasis is on temperature contrast and repetition, not extreme durations.

6) Choose exposure type based on how directly it hits skin cold receptors

Different cold methods likely differ because they affect skin receptors differently:

• Cold water immersion (up to neck): strong activation (molecules closer to skin; more total-body cooling)
• Cold wind / being outside in a t-shirt: can still activate sympathetic activity, but likely less intense than full immersion
• Cold shower: assumed intermediate; harder to study precisely in controlled settings

7) Understand/target brown fat as a metabolism lever

Cold and heat are discussed as ways to activate brown fat thermogenesis (more mitochondrial activity → more heat production).

Key points:

• Brown fat is described as more plastic than once thought:
  • It can grow or decrease depending on activation (e.g., via norepinephrine signaling)
• Brown fat is linked to:
  • Higher metabolism
  • Improved insulin sensitivity
  • Potential improvements in blood glucose clearance
  • Possibly lower inflammation markers

8) Heat (sauna) is also a hormetic stressor

Heat exposure is framed as:

• Supporting cardiometabolic benefits with a time ceiling

In this discussion, the idea is:

• There’s a “healthy stress window,” not a “longer is better” rule.

9) Cold exposure may improve metabolic markers and blood pressure (in her research context)

Compared with matched controls in the winter-swimmers context, she reports:

• Increased insulin sensitivity
• Lower insulin production
• Faster glucose clearance
• Lower blood pressure / lower heart rate outcomes reported from related literature her discussion references

Mechanistic link suggested:

• Reduced inflammation + improved metabolic regulation

10) Cold exposure may influence mood via neurotransmitters and inflammation pathways

She connects:

• Catecholamine shifts (dopamine/epinephrine/norepinephrine) to mood
• Reduced inflammatory signaling (examples mentioned: IL-6, IL-10 axis) to possible effects on:
  • anxiety/depression risk
  • neurodegenerative risk factors (e.g., Alzheimer’s associations discussed)

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Safety & practical cautions explicitly implied or discussed

• Avoid hypothermia: cold adaptation isn’t the goal; “healthy stress” is.
• Beginners: may experience strong responses (hyperventilation/gasp reflex). Build gradually.
• Children / smaller bodies: less safe time window; they may defend core temperature for shorter durations.
• Wind/head exposure: head dunking may increase heat loss and affect brain blood flow; wearing a cap/beanie is suggested as a practical approach.
• Raynaud’s symptoms: direct studies are limited, but she notes mixed experiences:
  • some find it helps; others don’t
  • practical mitigation ideas include keeping hands out of cold or partial exposure, and using neoprene boots for feet.

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Presenters / sources

• Presenter/Host: Andrew Huberman (Huberman Lab; Stanford)
• Guest/Researcher: Dr. Susanna Søberg
• Organizations/Items mentioned (contextual sponsors): Plunge, Maui Nui Venison, Thesis, AG1/Athletic Greens, InsideTracker, Momentous (and other podcast-related references)
• Named study types/authors (mentioned in discussion, not fully enumerated):
  • studies on brown fat activation
  • insulin sensitivity
  • sauna/cardiovascular thresholds (e.g., “Finnish cohort study,” “Hansen 2017” for cold-room sleeping)
  • other referenced clinical/physiology research