What My 2023 Cold-Plunge Diary Actually Recorded

BLUF

From February 20 through May 1, 2023, I kept a simple cold-plunge diary. I began with two-minute sessions in water at or below about 52°F and gradually worked up to five and a half minutes at or below about 50°F. The most important entries were not the longer times. They were the serious headaches I recorded after my earliest sessions.

The headaches eventually stopped, and my migraines later disappeared. That is part of my personal history, but I cannot say cold immersion caused either outcome. This diary is a record of what I did and felt—not a medical claim, a beginner’s program, or a protocol anyone else should copy.

This post is personal history, not medical advice. Anyone with health concerns should consult a qualified medical professional before trying cold-water immersion.

Where This Diary Fits in the PlungIT Story

The written log was not the beginning of my cold-plunge experiment. My wife and I first tested a chiller in our household bathtub in January 2023, while I was waiting for inflatable tubs to arrive from China. We were both doing CrossFit, and we wanted to see whether cold water felt useful after workouts.

By February, the experiment was becoming more deliberate. I began recording dates, minutes, approximate water temperatures, and days of the week in an Apple Note titled “Cold Plunge Beginners.” The title described me at the time. It did not mean I had created an evidence-based beginner’s guide.

I am publishing the diary now because its dates help preserve the project honestly. Memory can supply the larger story, but a dated note preserves the sequence—including the parts that were uncomfortable or incomplete.

The Log, Preserved as Closely as Possible

The table below transcribes the surviving note. I expanded a few abbreviations for readability but did not fill in sessions that were never recorded.

That is the complete surviving progression. It is uneven because real routines are uneven. One week has only a Friday entry. The final week has only Monday. The diary ends without a grand conclusion.

The Headache Entries Matter Most

My first week contains the bluntest line in the archive: “headaches serious afterwards?” The next week says they were still happening. I also noted that migraine medication helped.

I could have omitted that from the public version and left behind a neater story about discipline and gradually increasing my tolerance. That would also leave behind a less truthful one.

Cold-water immersion creates an immediate physiological stress response. The initial cold shock can sharply alter breathing, heart rate, and blood pressure. That does not explain the cause of my headaches, but it is one reason I would never tell someone to treat my temperatures and times as instructions.

The headaches eventually stopped. My migraines later disappeared as well. I am grateful for that outcome, but chronology is not causation. I did not conduct a controlled experiment, and many other factors in my health and life could have changed. I am preserving what happened to me without claiming that cold plunging treats or cures migraines.

Progression Is Not Proof of a Universal Protocol

My old note began with a plan to “start from 2 minutes and work up to 10 minutes.” I never documented reaching ten minutes. I also wrote down ideas such as starting between 50°F and 59°F, plunging several days per week, waiting before exercising, and accumulating a minimum number of minutes each week.

Those were working notes gathered by a beginner in 2023, not conclusions I had validated. I would not present them today as universal guidance.

The modern research is more conditional than social-media slogans make it sound. Reviews have found that cold-water immersion can help with some measures of soreness and short-term recovery after strenuous exercise, but outcomes depend on the activity, timing, temperature, duration, and the result being measured. Regular cold immersion used with resistance training may also reduce some long-term strength adaptations. A 2025 review of health and wellbeing found some time-dependent effects but emphasized the limited number of trials, small samples, and lack of participant diversity.

In other words, there is no single magic combination of “colder” and “longer” that is automatically better for everyone.

What the Diary Taught Me

The best thing I did was take notes.

Without this log, I might remember only that I began around two minutes and later stayed in longer. The document shows something more useful: how gradually I increased, where the routine broke, how cold one session became, and when my body gave me a reason to pay attention.

It also reminds me that a personal experiment should have stopping rules. A severe or unexpected symptom is information, not an obstacle to push through for the sake of a streak. Someone considering cold-water immersion—especially someone with a health condition or cardiovascular concern—should discuss it with a qualified clinician and avoid treating an internet diary as individualized advice.

Finally, the diary marks the point when a wellness experiment began turning into an engineering project. Once I was repeatedly trying to hold water near 50°F, the practical questions became unavoidable: How much water was I cooling? How long did it take? Was the chiller oversized? How much flow did the pump need? Which combination could work reliably in a portable tub?

Those questions led directly to the next stage of PlungIT.

The Record I Wanted to Leave Behind

This is not the story of an optimized routine. It is the record of a person learning in real time.

I started cautiously, experienced headaches, continued documenting what happened, and gradually spent more time in colder water. The surviving note ends on May 1, 2023, but by then the project had already expanded beyond the diary. I was measuring tubs, testing circulation, choosing chillers and pumps, and working toward a product another person could actually use.

The log matters because it anchors that larger story to specific days. PlungIT was not invented later as a piece of marketing. I was there, the water was cold, the headaches were real, and I wrote it down.

This post is part of the PlungIT project archive. Start with the complete PlungIT pillar story, or read the preceding chapter, Before PlungIT, There Was a Chiller in My Bathtub. Next: how I matched the chiller and circulation pump to the tub.

Sources and Further Reading

• American Heart Association — The plunge into cold water comes with risks
• Moore et al. — Impact of Cold-Water Immersion Compared with Passive Recovery Following Strenuous Exercise
• Batista et al. — Parameters Influencing Cold-Water Immersion and Muscle Soreness
• Malta et al. — Regular Cold-Water Immersion During Training
• Cain et al. — Effects of Cold-Water Immersion on Health and Wellbeing