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Sauna Hype

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We read Bryan Johnson's sauna experiment the way a peer reviewer would.

In May 2025 Bryan Johnson started taking a 20-minute sauna at 93°C every day, and he measured almost everything he could.Source 1 · Web pageThread asking whether sauna is worth the hypeJohnson B. Post on X, May 7, 2025, 2025.Read the page ↗ He tracked chemicals in his urine, microplastics in his blood and semen, his sperm, his blood pressure and later his core temperature, and he posted the results as he went.Source 2 · Web pagePost with his full sauna resultsJohnson B. Post on X, December 6, 2025, 2025.Read the page ↗ He has also been clear that one person's results can't prove cause.Source 3 · Web pagePost reporting no microplastics in his semenJohnson B. Post on X, May 7, 2026, 2026.Read the page ↗ Scroll to see the tests in the order they happened, and how each one holds up to a scientist's checklist.

By Adam BognarSep 24, 20269 min readThe calendar zooms as you scroll.

Scroll to open the calendar ↓

Nov ’24Jan ’25MarMayJulSepNovJan ’26MarMayJul20 minutes a day at 93°Clonger sessions93 sessions in 200 daysless plastic, then filtered waterWhat he postedDaily saunaLA wildfiresPlasma exchangeHyperbaric oxygenLess plastic at homeGrowth hormone peptideUrine solvent markerMicroplastics in bloodMicroplastics in semenSpermCentral blood pressureWaking temperatureMinutes to a 39°C coreDay 1 of sauna

Sept 2024 to July 2026

Each row tracks one thing he measured or changed

The top rows show what else was going on in his life while the tests ran. There's a wildfire, a course of plasma exchange, nearly a hundred sessions in a hyperbaric oxygen chamber and a push to get plastic out of his home.Source 4 · Web pagePalisades Fire incident pageCAL FIRE. California Department of Forestry and Fire Protection, 2025.Read the page ↗Source 5 · Web pagePost on his first total plasma exchangeJohnson B. Post on X, October 14, 2024, 2024.Read the page ↗Source 6 · Web pagePost on 93 hyperbaric oxygen sessions in 200 daysJohnson B. Post on X, May 11, 2025, 2025.Read the page ↗Source 7 · Web pagePost saying he cut the microplastics in his blood by 93%Johnson B. Post on X, June 23, 2025, 2025.Read the page ↗

His test results fill the rows underneath. The orange line marks his first day of daily sauna.

May 2025

He held off for two years, then tested the sauna on himself

In 2023 he wrote that his Blueprint program had no sauna protocol, because his team hadn't found evidence that it slowed his aging.Source 8 · Web pagePost explaining why Blueprint had no sauna protocolJohnson B. Post on X, May 4, 2023, 2023.Read the page ↗ A year later he still called the evidence thin for healthy people.Source 9 · Web pagePost saying sauna was not part of his routineJohnson B. Post on X, May 29, 2024, 2024.Read the page ↗

On May 7, 2025, he announced a self-test of 20 minutes a day at 93°C, with an ice pack on his groin to protect his sperm.Source 1 · Web pageThread asking whether sauna is worth the hypeJohnson B. Post on X, May 7, 2025, 2025.Read the page ↗Source 10 · Web pagePost in the same thread giving his sauna protocolJohnson B. Post on X, May 7, 2025, 2025.Read the page ↗ His posts put day one between May 5 and May 8.Source 11 · Web pagePost on day seven of daily saunaJohnson B. Post on X, May 11, 2025, 2025.Read the page ↗Source 12 · Web pagePost on his vascular readings after seven daysJohnson B. Post on X, May 15, 2025, 2025.Read the page ↗

October 2024 to May 2025

Other treatments overlapped with the sauna test

On October 14, 2024, he had his first total plasma exchange, which drains the liquid part of the blood and replaces it with a protein solution. He planned six and later said he'd done four.Source 5 · Web pagePost on his first total plasma exchangeJohnson B. Post on X, October 14, 2024, 2024.Read the page ↗Source 13 · Web pageReply on four plasma exchanges and his toxin levelsJohnson B. Post on X, December 6, 2025, 2025.Read the page ↗ By May 11, 2025, he'd also logged 93 sessions in a hyperbaric oxygen chamber over 200 days.Source 6 · Web pagePost on 93 hyperbaric oxygen sessions in 200 daysJohnson B. Post on X, May 11, 2025, 2025.Read the page ↗

He set out to get as much plastic out of his life as he could, and later listed a water filter and new cutting boards among the changes.Source 7 · Web pagePost saying he cut the microplastics in his blood by 93%Johnson B. Post on X, June 23, 2025, 2025.Read the page ↗Source 14 · Web pagePost on his November 2025 blood microplastics resultJohnson B. Post on X, December 17, 2025, 2025.Read the page ↗ In January the Palisades fire burned for more than three weeks in Los Angeles.Source 4 · Web pagePalisades Fire incident pageCAL FIRE. California Department of Forestry and Fire Protection, 2025.Read the page ↗ Any of these could move the same numbers the sauna was meant to move, so a reviewer would look at them first.

Toxins

His urine readings were already falling before the sauna began

In June 2025 he reported that 15 sauna sessions lowered seven chemicals in his urine by 15% to 100%.Source 15 · Web pagePost saying 15 sauna sessions reduced his toxinsJohnson B. Post on X, June 18, 2025, 2025.Read the page ↗ His comparison ran from a test on March 26 to one on May 22.

The calendar adds an earlier test. During the January fires the solvent marker NAPR read 91.98 on the lab's scale, and by March 26 it was down to 12.92 with no sauna at all. The sauna window covers the next step, to 5.75.Source 16 · Web pageThread on the LA fires and his urine toxin panelJohnson B. Post on X, February 28, 2025, 2025.Read the page ↗Source 15 · Web pagePost saying 15 sauna sessions reduced his toxinsJohnson B. Post on X, June 18, 2025, 2025.Read the page ↗

Toxins

A urine test mostly records the last day or two

The chemicals on his panel are breakdown products that the body clears within hours. After a test dose of the plastic softener DEHP, its breakdown product peaked in urine at two hours and had a half-life of about five hours.Source 17 · Clinical trialDi(2-ethylhexyl)phthalate (DEHP) metabolites in human urine and serum after a single oral dose of deuterium-labelled DEHPKoch HM, Bolt HM, Angerer J. Archives of Toxicology, 2004.Read the paper ↗PubMed ↗ The weedkiller 2,4-D leaves urine with a half-life of about 18 hours.Source 18 · Clinical trialThe fate of 2,4-dichlorophenoxyacetic acid (2,4-D) following oral administration to manSauerhoff MW, Braun WH, Blau GE, et al.. Toxicology, 1977.Read the paper ↗PubMed ↗

So each test mostly shows what he was exposed to the day before, and single samples from the same person can vary widely from one day to the next. That's why researchers who study these chemicals collect several samples before and after a change.Source 19 · Cohort studyTemporal variability of urinary phthalate metabolite levels in men of reproductive ageHauser R, Meeker JD, Park S, et al.. Environmental Health Perspectives, 2004.Read the paper ↗PubMed ↗

Microplastics in blood

His blood test counted seven particles, then one

In June 2025 he posted that the microplastics in his blood had fallen 93%.Source 7 · Web pagePost saying he cut the microplastics in his blood by 93%Johnson B. Post on X, June 23, 2025, 2025.Read the page ↗ The test stains a finger-prick spot of dried blood and counts particles under a microscope.Source 20 · Web pageHow does the test work?Blueprint. Blueprint help centre, 2026.Read the page ↗ The lab assumes each sample holds a tenth of a milliliter and multiplies its count by ten, so his October result of 70 per milliliter means seven particles and his May result means one.Source 7 · Web pagePost saying he cut the microplastics in his blood by 93%Johnson B. Post on X, June 23, 2025, 2025.Read the page ↗

Counts that small can move a lot by chance. A 2026 pilot study that used the same kind of kit called its own results semi-quantitative.Source 21 · Cross-sectional studyThe Association of Microplastics in Peripheral Blood and Pulmonary Disease: A Pilot StudyHelgeson SA, Alaws H, Ibrahim MI, et al.. Journal of Xenobiotics, 2026.Read the paper ↗PubMed ↗

Microplastics in blood

The blood draw may have come before his first session

The one-particle result came in a report dated May 25, 2025, less than three weeks into the sauna habit. The test's product page quotes a turnaround of four to six weeks, which would put the blood draw in April, and the report doesn't show a collection date.Source 7 · Web pagePost saying he cut the microplastics in his blood by 93%Johnson B. Post on X, June 23, 2025, 2025.Read the page ↗Source 22 · Brand pageMicroplastics Test (product page)Blueprint. Blueprint store, 2026.Read the page ↗

Plasma exchange and the oxygen chamber also ran in the months between the two tests. In June he listed plasma exchange and plastic removal alongside the sauna as possible causes.Source 7 · Web pagePost saying he cut the microplastics in his blood by 93%Johnson B. Post on X, June 23, 2025, 2025.Read the page ↗

Microplastics in semen

He says himself that the semen result can't prove cause

In October 2025 he reported an 85% drop in microplastics in his semen, from 165 particles per milliliter to 20, and named the sauna as the likeliest reason.Source 23 · Web pagePost saying he eliminated 85% of microplastics from his ejaculateJohnson B. Post on X, October 21, 2025, 2025.Read the page ↗ An April 2026 test found none.

Announcing that result, he wrote that he'd switched to filtered water and cut out plastic in the same stretch, so he couldn't prove cause, and that the particles are too big to sweat out.Source 3 · Web pagePost reporting no microplastics in his semenJohnson B. Post on X, May 7, 2026, 2026.Read the page ↗ Labs also count these particles in very different ways. Studies that identify each particle's plastic chemically have found fewer than 4 per milliliter of semen.Source 24 · Cross-sectional studyDetection and characterization of microplastics in the human testis and semenZhao Q, Zhu L, Weng J, et al.. Science of the Total Environment, 2023.Read the paper ↗PubMed ↗Source 25 · Cross-sectional studyMicroplastics in human semen: Physicochemical characterisation and surface-associated elemental profiles among Malaysian menPraveena SM, Mohd Roslee SA, Asraf AZ, et al.. Environmental Research, 2026.Read the paper ↗PubMed ↗

Sperm

His ice test is the kind of experiment scientists run

In late June 2025 he ran 15 sessions without the groin ice pack on purpose. By July 8 the share of his sperm that could swim had fallen from 53% to 23%. It stayed low through two more tests while his total count dipped, and then it recovered.Source 26 · Web pageThread on three ice experiments, with dated semen resultsJohnson B. Post on X, July 23, 2025, 2025.Read the page ↗Source 2 · Web pagePost with his full sauna resultsJohnson B. Post on X, December 6, 2025, 2025.Read the page ↗

Controlled studies of scrotal heat show the same order of events. When researchers kept men's testes about 2°C warmer, motility dropped from about day 20 and sperm count from about day 34, and both recovered after the heating stopped.Source 27 · Clinical trialMild induced testicular and epididymal hyperthermia alters sperm chromatin integrity in menAhmad G, Moinard N, Esquerré-Lamare C, et al.. Fertility and Sterility, 2012.Read the paper ↗PubMed ↗ Motility varies little between one man's samples, so a fall this big stands out from chance.Source 28 · Cohort studyIntraindividual variability of semen quality, proteome, and sncRNA profiles in a healthy cohort of young adultsSergeyev O, Bezuglov V, Soloveva N, et al.. Andrology, 2025.Read the paper ↗PubMed ↗

Sperm

One man's sperm counts swing a lot from test to test

In November 2025 he posted a record of 330 million moving sperm.Source 29 · Web pagePost saying his fertility markers hit an all-time highJohnson B. Post on X, November 14, 2025, 2025.Read the page ↗ Counts like this vary widely in everyone. In 164 young men tested a week apart, the moving-sperm count changed by about 41% from one sample to the next.Source 28 · Cohort studyIntraindividual variability of semen quality, proteome, and sncRNA profiles in a healthy cohort of young adultsSergeyev O, Bezuglov V, Soloveva N, et al.. Andrology, 2025.Read the paper ↗PubMed ↗ Against his pre-sauna average of 165 million, a single result would need to top about 386 million to stand out from that swing.

His later tests covered the same kind of range. After psilocybin his count fell 69%, and a test 90 days later set a new record.Source 30 · Web pageMagic mushrooms dropped my sperm count 69%Johnson B. Bryan Johnson on Substack, May 4, 2026, 2026.Read the page ↗

Blood pressure

Most of the change in his arteries came in the first week

He tracked his arteries with a home cuff that estimates blood pressure close to the heart.Source 31 · Web pagePost giving his vascular baselineJohnson B. Post on X, May 13, 2025, 2025.Read the page ↗ That central pressure went from 103 to 97 mmHg in the first week and ended at 96, which he described as a 10-year drop in vascular age.Source 12 · Web pagePost on his vascular readings after seven daysJohnson B. Post on X, May 15, 2025, 2025.Read the page ↗Source 2 · Web pagePost with his full sauna resultsJohnson B. Post on X, December 6, 2025, 2025.Read the page ↗

Readings like this move from day to day. On the lab version of the device, repeat readings differ by about 7 to 9 mmHg, and one sauna session after exercise lowers central pressure by about 7 mmHg half an hour later.Source 32 · Clinical trialReliability of oscillometric central blood pressure and wave reflection readings: effects of posture and fastingYoung Y, Abdolhosseini P, Brown F, et al.. Journal of Hypertension, 2015.Read the paper ↗PubMed ↗Source 33 · Crossover trialStandalone sauna vs exercise followed by sauna on cardiovascular function in non-naïve sauna users: A comparison of acute effectsLee E, Kostensalo J, Willeit P, et al.. Health Science Reports, 2021.Read the paper ↗PubMed ↗ Several readings taken at the same time of day would separate a lasting change from that daily swing.

April 2026

A temperature pill led him to change his own protocol

In April 2026 he swallowed a pill that logs core temperature. It showed his core took 31 to 53 minutes in the sauna to reach 39°C, the level he treats as the threshold for heat shock proteins.Source 34 · Web pagePost on minutes to reach 39°C with and without face iceJohnson B. Post on X, April 3, 2026, 2026.Read the page ↗Source 35 · Web page31 brutal minutes to saunamaxxJohnson B. Bryan Johnson on Substack, April 14, 2026, 2026.Read the page ↗Source 36 · Web pagePost on a growth hormone peptide and his time to reach 39°CJohnson B. Post on X, May 6, 2026, 2026.Read the page ↗ His daily sessions had been 20 minutes, so he posted “I think I need to be fired” and started staying in longer.Source 37 · Web pagePost saying his 20-minute protocol never reached the heat shock thresholdJohnson B. Post on X, April 6, 2026, 2026.Read the page ↗Source 35 · Web page31 brutal minutes to saunamaxxJohnson B. Bryan Johnson on Substack, April 14, 2026, 2026.Read the page ↗

The 39°C figure comes from white blood cells heated in a lab dish for two hours.Source 38 · Cell studyCell type-specific variations in the induction of hsp70 in human leukocytes by feverlike whole body hyperthermiaOehler R, Pusch E, Zellner M, et al.. Cell Stress and Chaperones, 2001.Read the paper ↗PubMed ↗ Studies of whole bodies are less clear, and a pooled analysis of 51 heating studies found heat shock proteins unchanged after single or repeated sessions.Source 39 · Meta-analysisHeat thermotherapy to improve cardiovascular function and cardiometabolic health: A systematic review and meta‐analysisPrice BS, Lucas SJE, Akerman AP, et al.. Experimental Physiology, 2025.Read the paper ↗PubMed ↗

Cold

The pill also gave him a truer reading of his body temperature

He doesn't cold plunge. In 2024 he described his waking temperature of 93.4°F as minor hypothermia.Source 40 · Brand pagePeople often ask if I cold plunge. The answer is that I don't and here's whyJohnson B. Blueprint blog, November 29, 2024, 2024.Read the page ↗Source 41 · Web pagePost giving his waking body temperature as 93.4°FJohnson B. Post on X, November 22, 2024, 2024.Read the page ↗ He took that reading with an ear thermometer.

The pill logged his waking low at 96.1°F, above the 95°F line where hypothermia starts.Source 42 · Web pageX article on core temperature in the saunaJohnson B. Post on X, April 2, 2026, 2026.Read the page ↗Source 43 · ReviewAccidental Hypothermia: 2021 UpdatePaal P, Pasquier M, Darocha T, et al.. International Journal of Environmental Research and Public Health, 2022.Read the paper ↗PubMed ↗ Ear thermometers can miss a cold body's core temperature by about 2°C, so the pill is the better instrument.Source 44 · Meta-analysisAccuracy of peripheral thermometers for estimating temperature: a systematic review and meta-analysisNiven DJ, Gaudet JE, Laupland KB, et al.. Annals of Internal Medicine, 2015.Read the paper ↗PubMed ↗

What the calendar shows

His ice test shows what a strong one-person trial looks like

Most of his results compare one sample before a change with one sample after it, with other treatments running alongside. The ice test switched one thing off on purpose and then back on, and his sperm moved with it.Source 26 · Web pageThread on three ice experiments, with dated semen resultsJohnson B. Post on X, July 23, 2025, 2025.Read the page ↗ Planned in advance and repeated, that design is called an n-of-1 trial, and clinicians use it to test a treatment in a single patient.Source 45 · GuidanceCONSORT extension for reporting N-of-1 trials (CENT) 2015: explanation and elaborationShamseer L, Sampson M, Bukutu C, et al.. Journal of Clinical Epidemiology, 2016.Read the paper ↗PubMed ↗

One person, done right

Five changes would turn his sauna log into an n-of-1 trial

He has already done the hard part, which is measuring and publishing. Single-person trials have a reporting standard of their own, and it favors planned periods on and off a treatment.Source 45 · GuidanceCONSORT extension for reporting N-of-1 trials (CENT) 2015: explanation and elaborationShamseer L, Sampson M, Bukutu C, et al.. Journal of Clinical Epidemiology, 2016.Read the paper ↗PubMed ↗ These five changes would let his sauna data answer the question he set out to test.

  1. Change 1

    Switch the sauna on and off in planned blocks

    Alternate weeks with and without the sauna in an order set in advance, the way he did with the ice.Source 26 · Web pageThread on three ice experiments, with dated semen resultsJohnson B. Post on X, July 23, 2025, 2025.Read the page ↗

  2. Change 2

    Hold the other treatments still

    Pause plasma exchange, the oxygen chamber, peptides and household changes while the blocks run.

  3. Change 3

    Take several baseline samples

    Two or three samples before each switch, from the same lab, give a baseline that one odd result can't swing. One man's sperm counts can vary by 40% between samples.Source 28 · Cohort studyIntraindividual variability of semen quality, proteome, and sncRNA profiles in a healthy cohort of young adultsSergeyev O, Bezuglov V, Soloveva N, et al.. Andrology, 2025.Read the paper ↗PubMed ↗

  4. Change 4

    Publish the whole panel

    His urine panel covers 27 chemicals. Posting all of them, including any that rose, lets readers see the full picture.Source 46 · Web pageReply to David Sinclair after 48 sauna sessionsJohnson B. Post on X, July 15, 2025, 2025.Read the page ↗

  5. Change 5

    Fit each block to what it measures

    Urine chemicals turn over in days. Sperm take about 64 days to form, so a semen block needs at least ten weeks.Source 47 · Clinical trialSpermatogenesis in man: an estimate of its durationHeller CG, Clermont Y. Science, 1963.Read the paper ↗PubMed ↗

This story touches these claims

90°H

Hot air

Heat

“A sauna sweats microplastics out of your body.”

68°H

Stretched

Heat

“You can sweat out toxins in a sauna.”

30°H

Likely

Heat

“Regular sauna use lowers your sperm count.”

74°H

Stretched

Heat

“Sauna switches on heat shock proteins that slow aging.”

44°H

Early

Heat

“Sauna lowers your blood pressure.”

61°H

Stretched

Heat

“Sauna makes your arteries more flexible.”

We built the calendar from his own posts

Every date and value comes from Johnson's posts on X, his Blueprint blog and his Substack, read in September 2026. Where he gave only a month, the point goes at mid-month. Hollow points mark dates we worked out from his descriptions, such as a sample he labeled four weeks after the no-ice sessions.

The urine values are his lab's figures for NAPR in micrograms per gram of creatinine. The blood microplastics reports turn a particle count into a concentration by assuming a sample of a tenth of a milliliter. His June 2025 post described the October result as 15 particles, which doesn't match that conversion.Source 7 · Web pagePost saying he cut the microplastics in his blood by 93%Johnson B. Post on X, June 23, 2025, 2025.Read the page ↗

The normal-swing band on the sperm chart is our calculation. It uses the variation Sergeyev and colleagues measured between one man's samples, set against a baseline of five tests averaging 165 million.Source 28 · Cohort studyIntraindividual variability of semen quality, proteome, and sncRNA profiles in a healthy cohort of young adultsSergeyev O, Bezuglov V, Soloveva N, et al.. Andrology, 2025.Read the paper ↗PubMed ↗Source 48 · Brand pageMy Sperm Health ProtocolJohnson B. Blueprint blog, June 10, 2025, 2025.Read the page ↗ The noise band on the blood pressure chart spans 8 mmHg either side of his first reading, in line with repeat readings on the lab version of his device.Source 32 · Clinical trialReliability of oscillometric central blood pressure and wave reflection readings: effects of posture and fastingYoung Y, Abdolhosseini P, Brown F, et al.. Journal of Hypertension, 2015.Read the paper ↗PubMed ↗

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We cited these sources

  1. 01Johnson B. Thread asking whether sauna is worth the hype. Post on X, May 7, 2025. 2025. Accessed Sep 24, 2026.
  2. 02Johnson B. Post with his full sauna results. Post on X, December 6, 2025. 2025. Accessed Sep 24, 2026.
  3. 03Johnson B. Post reporting no microplastics in his semen. Post on X, May 7, 2026. 2026. Accessed Sep 24, 2026.
  4. 04CAL FIRE. Palisades Fire incident page. California Department of Forestry and Fire Protection. 2025. Accessed Sep 24, 2026.
  5. 05Johnson B. Post on his first total plasma exchange. Post on X, October 14, 2024. 2024. Accessed Sep 24, 2026.
  6. 06Johnson B. Post on 93 hyperbaric oxygen sessions in 200 days. Post on X, May 11, 2025. 2025. Accessed Sep 24, 2026.
  7. 07Johnson B. Post saying he cut the microplastics in his blood by 93%. Post on X, June 23, 2025. 2025. Accessed Sep 24, 2026.
  8. 08Johnson B. Post explaining why Blueprint had no sauna protocol. Post on X, May 4, 2023. 2023. Accessed Sep 24, 2026.
  9. 09Johnson B. Post saying sauna was not part of his routine. Post on X, May 29, 2024. 2024. Accessed Sep 24, 2026.
  10. 10Johnson B. Post in the same thread giving his sauna protocol. Post on X, May 7, 2025. 2025. Accessed Sep 24, 2026.
  11. 11Johnson B. Post on day seven of daily sauna. Post on X, May 11, 2025. 2025. Accessed Sep 24, 2026.
  12. 12Johnson B. Post on his vascular readings after seven days. Post on X, May 15, 2025. 2025. Accessed Sep 24, 2026.
  13. 13Johnson B. Reply on four plasma exchanges and his toxin levels. Post on X, December 6, 2025. 2025. Accessed Sep 24, 2026.
  14. 14Johnson B. Post on his November 2025 blood microplastics result. Post on X, December 17, 2025. 2025. Accessed Sep 24, 2026.
  15. 15Johnson B. Post saying 15 sauna sessions reduced his toxins. Post on X, June 18, 2025. 2025. Accessed Sep 24, 2026.
  16. 16Johnson B. Thread on the LA fires and his urine toxin panel. Post on X, February 28, 2025. 2025. Accessed Sep 24, 2026.
  17. 17Koch HM, Bolt HM, Angerer J. Di(2-ethylhexyl)phthalate (DEHP) metabolites in human urine and serum after a single oral dose of deuterium-labelled DEHP. Archives of Toxicology. 2004;78(3):123-30. doi:10.1007/s00204-003-0522-3 PMID 14576974
  18. 18Sauerhoff MW, Braun WH, Blau GE, Gehring PJ. The fate of 2,4-dichlorophenoxyacetic acid (2,4-D) following oral administration to man. Toxicology. 1977;8(1):3-11. doi:10.1016/0300-483x(77)90018-x PMID 929615
  19. 19Hauser R, Meeker JD, Park S, Silva MJ, Calafat AM. Temporal variability of urinary phthalate metabolite levels in men of reproductive age. Environmental Health Perspectives. 2004;112(17):1734-40. doi:10.1289/ehp.7212 PMID 15579421
  20. 20Blueprint. How does the test work?. Blueprint help centre. 2026. Accessed Sep 24, 2026.
  21. 21Helgeson SA, Alaws H, Ibrahim MI, Lee AS, Vlecken DHW, Baig HZ. The Association of Microplastics in Peripheral Blood and Pulmonary Disease: A Pilot Study. Journal of Xenobiotics. 2026;16(3). doi:10.3390/jox16030072 PMID 42201067
  22. 22Blueprint. Microplastics Test (product page). Blueprint store. 2026. Accessed Sep 24, 2026.
  23. 23Johnson B. Post saying he eliminated 85% of microplastics from his ejaculate. Post on X, October 21, 2025. 2025. Accessed Sep 24, 2026.
  24. 24Zhao Q, Zhu L, Weng J, Jin Z, Cao Y, Jiang H, et al.. Detection and characterization of microplastics in the human testis and semen. Science of the Total Environment. 2023;877:162713. doi:10.1016/j.scitotenv.2023.162713 PMID 36948312
  25. 25Praveena SM, Mohd Roslee SA, Asraf AZ, Nekmat NW, Abu Hassan YS, Samad NA, et al.. Microplastics in human semen: Physicochemical characterisation and surface-associated elemental profiles among Malaysian men. Environmental Research. 2026;299:124348. doi:10.1016/j.envres.2026.124348 PMID 41903729
  26. 26Johnson B. Thread on three ice experiments, with dated semen results. Post on X, July 23, 2025. 2025. Accessed Sep 24, 2026.
  27. 27Ahmad G, Moinard N, Esquerré-Lamare C, Mieusset R, Bujan L. Mild induced testicular and epididymal hyperthermia alters sperm chromatin integrity in men. Fertility and Sterility. 2012;97(3):546-53. doi:10.1016/j.fertnstert.2011.12.025 PMID 22265039
  28. 28Sergeyev O, Bezuglov V, Soloveva N, Smigulina L, Denisova T, Dikov Y, et al.. Intraindividual variability of semen quality, proteome, and sncRNA profiles in a healthy cohort of young adults. Andrology. 2025;13(4):840-859. doi:10.1111/andr.13739 PMID 39230333
  29. 29Johnson B. Post saying his fertility markers hit an all-time high. Post on X, November 14, 2025. 2025. Accessed Sep 24, 2026.
  30. 30Johnson B. Magic mushrooms dropped my sperm count 69%. Bryan Johnson on Substack, May 4, 2026. 2026. Accessed Sep 24, 2026.
  31. 31Johnson B. Post giving his vascular baseline. Post on X, May 13, 2025. 2025. Accessed Sep 24, 2026.
  32. 32Young Y, Abdolhosseini P, Brown F, Faulkner J, Lambrick D, Williams MA, et al.. Reliability of oscillometric central blood pressure and wave reflection readings: effects of posture and fasting. Journal of Hypertension. 2015;33(8):1588-93. doi:10.1097/HJH.0000000000000604 PMID 26136065
  33. 33Lee E, Kostensalo J, Willeit P, Kunutsor SK, Laukkanen T, Zaccardi F, et al.. Standalone sauna vs exercise followed by sauna on cardiovascular function in non-naïve sauna users: A comparison of acute effects. Health Science Reports. 2021;4(4):e393. doi:10.1002/hsr2.393 PMID 34622026
  34. 34Johnson B. Post on minutes to reach 39°C with and without face ice. Post on X, April 3, 2026. 2026. Accessed Sep 24, 2026.
  35. 35Johnson B. 31 brutal minutes to saunamaxx. Bryan Johnson on Substack, April 14, 2026. 2026. Accessed Sep 24, 2026.
  36. 36Johnson B. Post on a growth hormone peptide and his time to reach 39°C. Post on X, May 6, 2026. 2026. Accessed Sep 24, 2026.
  37. 37Johnson B. Post saying his 20-minute protocol never reached the heat shock threshold. Post on X, April 6, 2026. 2026. Accessed Sep 24, 2026.
  38. 38Oehler R, Pusch E, Zellner M, Dungel P, Hergovics N, Homoncik M, et al.. Cell type-specific variations in the induction of hsp70 in human leukocytes by feverlike whole body hyperthermia. Cell Stress and Chaperones. 2001;6(4):306-15. doi:10.1379/1466-1268(2001)006<0306:ctsvit>2.0.co;2 PMID 11795467
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  40. 40Johnson B. People often ask if I cold plunge. The answer is that I don't and here's why. Blueprint blog, November 29, 2024. 2024. Accessed Sep 24, 2026.
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