How Cold and How Long?

bio-individuality health cold plunge practices cold therapy benefits cold water immersion cold water therapy techniques immersion therapy individuality mind-body wellness optimal cold water temperature Feb 20, 2024

Bio-Individuality and Variables Affecting Responses to Cold Water Immersion
by John Richter and Robyn Landis

Two of the most frequently asked questions about how to create a cold-water immersion practice are:
How cold should the water be, and
How long should I stay in?

After hearing from thousands of people worldwide since 2014 about what works and doesn't for them personally, we can say with 100% certainty the answer is: it depends! We have heard from people with autoimmune disease who find complete relief of their symptoms when they spend 20-30 minutes in water around 65˚ F (18˚ C). We have also heard from those who want to challenge themselves mentally and spend time in water at or below freezing for two to five minutes. Some push to ten or 20 minutes and longer.

Most people are happy to share what works for them and about their journey of discovery. It's great to see people's people's passion about cold water.

We do not, however, enjoy seeing people fight, argue, or insist that their way is the right way—the only way. They may reference their personal experience, a research paper, podcast, or influencer or simply make the assertion.

The wide range of answers speaks to the fact that each person is unique and has unique needs. We refer to this as bio-individuality. Add to our bio-individual responses the many variables regarding season, location, ambient temperature, and cold-water setup, and you realize there are endless potentials for temperature and duration that can produce different responses and results.
While there are many recommendations from credible trainers and educators in the cold-water immersion space—some of them backed by research—these recommendations may not benefit YOU and your practice.


With all due respect to The Mandalorian, there is no "The Way" when it comes to cold water immersion. There are many ways, and what works for one might not work for another. Further, what works for you on a given day, may not work for you tomorrow, next week, or at some point in the future.
At the end of this article, you'll find a list of 30+ variables in nine categories that can affect how you respond to cold water immersion.

More importantly, we discuss a framework for creating, continuing, or restarting a sustainable cold-water immersion practice.

We would love to hear from you. Let us know about your experience—at what temperature and duration you started, what works for you now, what variables most impact your practice, and what you learned along the way.

Framework for Cold Water Immersion Practice

This five-step framework offers one way—a way—to approach your cold water immersion practice, with the goal of optimizing benefits long term. Each step will be explored in further detail.   

  1. Discover your optimal dose
  2. Start warmer 
  3. Attunement
  4. Build time / reduce temperature
  5. Gradual progress

Understanding Dose

The company Plunge has a banner that says, “Cold is My Medicine.” If we take that perspective, two variables make up the dose: 

  • the water temperature, and 
  • how long you stay in. 

The Greek physician and alchemist Paracelsus said, “The right dose differentiates a poison and a remedy.”

With that in mind, here are a few definitions:

  • Minimal Effective Dose (MED) is the lowest amount of a substance or activity needed to produce an effect or benefit. 
  • Optimal Effective Dose (OED) is the amount that provides the most benefits.  
  • Point of Diminishing Return (PDR) is the amount beyond which there are no additional benefits or not enough additional benefits to make the increase worthwhile.
  • Adverse Reaction (AR) is an unintended or harmful side effect outside of the intended benefit. Hypothermia is a legitimate risk, and the initial side effects can include shivering, lethargy, and impaired judgment. 
  • Lethal Dose (LD) is the amount of exposure to a substance or condition that ends life. The final symptom of hypothermia is death.  

How do you determine your Optimal Effective Dose?
Two basic methods are available. The first is subjective/intuitive, and the second is objective/measured. Either way, determining your Optimal Effective Dose takes awareness and time. It can also change based on one or more variables listed. Each time you cold plunge can be a new experience and an invitation to pay attention to what you need at that moment.

Start Warmer

If you’re just starting your cold water immersion practice, we suggest you start with warmer water. If you’ve practiced with colder water but have been on a break, it’s also a good idea to reboot your practice with warmer water. 

How warm is “warmer cold water?” It could be anywhere between 50 to 65˚ F (10 to 28˚ C). If you have any concerns, start with 60 to 65˚ F (16˚ to 28˚ C).


Attunement is simply noticing what is going on with your body. It could also be called mindfulness, awareness, witness consciousness, or simply paying attention. It can be subjective or objective. 

Subjective attunement is using your intuition or gut feeling. Some people call this the woo-factor. 

Objective attunement measures specific metrics with biofeedback devices. 

This attunement can be thought of as the art of your practice.

Subjective / Gut Feeling
Notice how you feel physically, emotionally, and mentally while in the water and after you get out. 

Cold water immersion can (and some say should) be uncomfortable, but it should not be painful

Hypothermia is a serious medical condition. The following symptoms might indicate the early stages of hypothermia. If you notice any of the following, it might be time—or past time— to get out of the water.

  • shivering
  • stabbing
  • burning
  • pins and needles
  • numbness
  • sluggishness 

Some people are fine pushing past these physical symptoms. Others, can end up harming themselves physically, mentally, or emotionally.

There can be a fine line between Optimal Effective Dose and Point of Diminishing Return. It can be difficult to notice where that line is until you’ve crossed it. This is one reason we recommend plunging with another person nearby.

Based on data collected by the United States Coast Guard about boating accidents, the time between the Point of Diminishing Return and Lethal Dose is significantly longer than the time between Optimal Effective Dose and Point of Diminishing Return

It is normal to feel some amount of nervousness before getting into cold water. However, if you are experiencing moderate or extreme anxiety or feelings of panic, we recommend getting out.

To Plunge, or Not to Plunge
To paraphrase Shakespeare, that is the question. It’s the first question to ask, and again you need to tune in to sense what is true and right in this moment.


Here are some of the decisions you can make with your practice on any given day when you ask yourself this question: 

  1. Get into the cold plunge
  2. Do not get into the cold plunge
  3. Get out of the water now
  4. Stay in the water longer

Intuitive decisions support your growth and well-being. 

One practice I’ve found to be helpful is to make a distinction between decisions that are intuitive versus those that are ego-driven. 

Ego-driven decisions may have deeper positive intentions (such as keeping you safe or helping you feel like you belong) but ultimately are not in your best interest. Ego-driven decisions can limit your growth long-term or cause harm. 

How can you tell if decisions are intuitive or ego-based? 

This in itself can be a skill and practice to develop. One thing I’ve noticed is that my intuition always has a simple, clear message. It can be a feeling, an image, or a voice: “Stay in.” “Get out.”

Ego-based decisions can be followed by a reason, excuse, justification, or any kind of mental chatter. 

While there can be a legitimate reason to not cold plunge—for example, you might be sick—the ego-based decision is more likely to come with strong emotions, comparison, or judgment, or to be persistent. 

Some examples of ego-based reasons are:

“Stay in, because ________.” Then fill in the blank with one or more thoughts. Here are a few we have heard:

  • Everyone else has been in longer than you
  • You don’t want to be a wimp 
  • You were in longer yesterday
  • You were in for less time yesterday
  • You can only grow if you push yourself

These thoughts don’t have to make any logical sense, or they could make perfect logical sense. 

What other ways have you used to practice attunement? 

Objective Biometrics
If you prefer a more scientific approach, consider a wearable device like a smartwatch, fitness tracker, or ring that gives objective, real-time feedback.



These devices can optimize your duration and recovery times for cold plunges, sauna sessions, or contrast therapy. Several biometrics could be useful. Here’s a list of relevant metrics that could provide valuable insights:

  1. Heart Rate (HR): Indicates the intensity of cardiovascular activity and stress levels. A significant change or entry into a different zone could signal the need to exit the sauna or cold plunge.
  2. Heart Rate Variability (HRV): Measures the variation in time between each heartbeat, which indicates autonomic nervous system balance and stress levels. Changes in HRV can suggest optimal recovery times and readiness for another session.
  3. Skin Temperature: Provides insights into the body’s external temperature, which can be crucial for understanding when to exit a sauna or cold plunge to avoid overheating or overcooling.
  4. Blood Oxygen Saturation (SpO2): Indicates how well oxygen is being sent to parts of the body furthest from the heart, including extremities. Both high temperatures and cold exposure can affect SpO2 levels. 
  5. Respiratory Rate: Your breathing rate can indicate stress levels and how well your body copes with the heat or cold. An increased rate may suggest a need for a break.

Remember that metrics from wearables may not be accurate in extreme temperatures or when practicing hyperventilated breath. 

Build Time / Reduce Temperature
Most people can stay in cold water (again, depending on how cold it is) for one to three minutes. However, even one second of sitting in cold water can be stressful for some people starting out. For others, it might be 30 seconds, a minute, or three minutes. Any amount of time can be terrifying—or amazing. 

Many people start off their cold plunge journeys with water temperatures in the 50 to 65˚ F (10 to 28˚ C) range and eventually lower into the 40s or even 30s; some stay in the 50s and do very well. 

A common rule of thumb is adapting well anywhere between two and five minutes before you go lower, but there may be benefits to longer plunges at the higher temps. Most find that longer than five minutes at the colder end of the spectrum invokes the law of diminishing returns. Again, these general rules of thumb will bend to your bio-individuality.

One notable exception to this is people with mental health issues such as depression or anxiety, most of whom seem to receive benefits when submerged in water that is near freezing. 

Celebrate any progress, but don’t be in a hurry to stay in for any arbitrary amount of time you may have heard about on social media, even if backed by research. 

We have met too many people over the years who pushed too cold, too long, too soon—and created a mild to severe traumatic experience around cold water immersion. This can result in procrastination or complete avoidance. 

Gradual Progress
Add time gradually while practicing attunement. If you want to pick an arbitrary time to build up to, that’s fine—just practice attunement while you do so. Remember your purpose and goals for doing cold water immersion. People practice cold water immersion for many reasons, including general health benefits, specific physical or mental effects, to mitigate particular health conditions, build resilience, and more. 

When you reach your Optimal Effective Dose at your starting temperature, lower the temperature by one or two degrees. There is no need to take a giant leap down. 

Practice at your new lower temperature until you reach your Optimal Effective Dose again. 

Then repeat until you discover YOUR optimal temperature and duration. 

Going Forward

Read through the variables at the end of this article. 

Tune into your body. Find what you need with your overall practice and what you need on any given day. 

Give yourself permission to push your edge—also to take time off. 

Have your practice serve you, and not the other way around. This mindset honors your growth and well-being. 

A Note About Cold Shaming

Sharing what works for you is perfectly fine. Give others permission to attune to their needs and plunge their way. 

We don’t want to shame ourselves or others for differences in time, temperature, or any other aspect of the practice. Respect the variables and variances. 

Suppose you’re a well-padded, healthy male plunging in Hawaii. In that case, it’s inappropriate to advise a 110-pound woman with an autoimmune disease in a Wisconsin winter how cold, how long, how often to plunge, or how she “should” feel about getting in. Unless you’ve been hired as a cold water immersion coach, or someone has specifically asked for your feedback, that kind of “advising” is inappropriate no matter your location or condition.

There is no “right” way to plunge. Getting into cold water is something to be proud of no matter how you do it! Our community celebrates everyone who gets in any time at any temp.

Happy cold plunging! 

List of Variables 

Here are the variables that can affect your response to cold water immersion. Let me know if I’ve left anything out.

  1. Environmental Factors
    • Water Temperature
    • Physical Factors
    • Duration of cold plunge
    • Body type
    • Blood type
    • Body fat percentage
    • Gender
    • Age
    • Genetics and DNA
    • Hormone levels
    • Diet
    • Hydration level
    • Rest and sleep quality
    • Stress (acute or chronic)
    • Fitness level
    • Health status
    • Medical conditions (e.g., cardiovascular issues, Raynaud’s disease)
  2. Psychological Factors 
    • Mental resilience
    • Mindset and mental approach
    • Subjective perception of comfort or discomfort 
    • Social support
    • Tracking your progress
    • Celebrating milestones
    • Unresolved trauma
    • Motivational style
  3. Preparation
    • Breathwork 
    • Meditation
    • Mindfulness
    • Exercise
  4. Cold Plunge Practices 
    • Position in water
    • Movement in (or circulation of) water
    • Submerging or leaving out specific body parts (e.g., hands or feet)
    • Head dunking at the beginning or end of your immersion 
    • Wearing protective clothing (ex. Neoprene socks)
    • How you dry off
    • Post-plunge routine
  5. Contrast Therapy
    • Sauna or hot tub use before or after cold plunging (contrast therapy)
    • Contrast therapy parameters
      • time spent in heat and cold
      • number of cycles
      • amount of time between cycles
    • Ending with hot or cold
  6. Monitoring and Measurement 
    • Monitoring biometrics (e.g., heart rate or HRV) 
    • Using a timer, stopwatch, or clock (or not)
  7. Adaptation and Routine 
    • Adaptation and acclimatization to cold
    • Over what length of time have you been practicing (days, months, years?)
    • Frequency of cold plunging (e.g., daily, weekly)
    • Taking breaks or time off
    • Cold plunging while ill
  8. Your Cold Plunge 
    • Accessibility
    • Cleanliness
    • Ease of use
    • Aesthetics
    • Comfort of tank
    • Cost to set up
    • Cost to operate/maintain 
    • Time of year (season)
    • Ambient temperature
    • External audio (music or spoken)
    • Décor
    • Ease and accessibility 
    • Lighting

Team thank you for reading and please follow and send some love to the creators of this wonderful resource on ICE and Cold.

Robyn Landis

Robyn Landis is an ACE-certified fitness professional, self-care
coach, bestselling author, nutritionist, herbalist, and energy healer.
Motivation is her specialty, rooted in self-love and joyful
self-nourishment as an act of service and gratitude. Her mission is to
help you know what you need and give it to yourself—joyfully, by
choice—for the body and energy that serves your highest

John Richter

After overcoming more than two years of brutal insomnia with a simple
cold plunge routine, John became passionate about sharing the benefits
of cold water immersion. Through his book, website, and social media
platforms, he has helped make cold water accessible to thousands of
people around the world. John is an author and has been studying
personal development since 1995. He advocates for people to become the
best version of themselves.


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