Articles

Research-first writing on sauna, heat, fertility, and men's health. What the evidence actually says, claims examined.

Sperm Freezing Success Rates Began With Roosters and Bulls. Men Read the Number Wrong.
In 1949, a research team in London published a short note in Nature showing that glycerol kept rooster sperm alive through freezing. That finding made long-term sperm storage possible. Four years later, clinicians reported the first human pregnancies from frozen sperm. So the procedure men now use to bank sperm for the future is older than IVF, older than the birth control pill, and older than the phrase fertility insurance.But the success rate attached to sperm freezing still carries marks from where it started. It was built as a lab... Read more...
Sauna for Weight Loss: The History of Cutting Water and Misreading the Scale
The scale drops after a sauna session. One to three pounds gone in 30 minutes. You did not lose fat. You lost water, and the number will be back by morning.Men have been sold sauna weight loss for decades. The idea did not come from fat loss research. It came from wrestlers and boxers who needed to hit a number on a scale for five minutes, then drink it all back before the fight. That history explains why sauna weight loss looks impressive and fails.A trick borrowed from wrestlersCombat sport... Read more...
Sperm Have a Calendar: The 90-Day Pre-Pregnancy Checklist for Men
For most of the 20th century, a pre-pregnancy checklist belonged to women. Fertility textbooks wrote about the "barren wife," and a man's contribution got reduced to one semen sample and a yes or no answer. That framing ignored a biological fact we now understand far better: sperm are not made on demand.A 1992 meta-analysis in the BMJ pooled 61 studies covering 1938 to 1990 and found average sperm concentration dropped from 113 million per milliliter to 66 million per milliliter over those five decades (Carlsen et al., BMJ, 1992). Researchers... Read more...
Male Fertility Treatment Costs Are Hiding in Your Partner's Bill
In 1991, a man with a low sperm count had two medical options: donor sperm or adoption. Neither addressed his own fertility, and the cost of treating male infertility did not appear anywhere because no treatment existed. Then Gianpiero Palermo and his team in Brussels published a paper in The Lancet describing pregnancies from injecting a single sperm directly into an egg. That technique, intracytoplasmic sperm injection, changed the money side of male fertility as much as the biology side. It gave men a medical answer for the first time,... Read more...
Lower Heat Doesn't Mean Lower Risk: Rethinking Infrared Sauna Safety for Men
An infrared sauna at 55 degrees Celsius doesn't announce itself the way a Finnish sauna at 90 degrees does. You sit down, the air feels almost comfortable, and for the first ten minutes you might wonder if the panels are even working. Then the sweat starts. Your skin heats from the inside out. That change in how heat arrives alters what counts as safe, and most infrared sauna guidance for men still reads like it was copied from a traditional sauna brochure.Drink water. Skip alcohol. Limit your time. Those basics... Read more...
Male Reproductive Health Tips: The Physical Environment Matters More Than the Supplement Aisle
Sperm concentration in men without known fertility problems fell by more than half across five decades, according to the largest meta-analysis of the trend (Levine et al., Human Reproduction Update, 2023). The research team first reported the decline in 2017, then updated the analysis with more countries and newer data. The pattern held.Most male reproductive health advice has not moved much. The standard list still orbits supplements, blood panels, and broad lifestyle talk. But the research keeps returning to something more physical. The testicles are an external organ. They sit... Read more...
From Her Problem to His Diagnosis: The Real History of Male Infertility Psychology
Before 1978, a couple who could not conceive was almost always told to start with the woman. Semen analysis existed, but doctors rarely made it the first line of inquiry. That sequencing changed with two events: the first IVF birth in 1978 and the first ICSI pregnancy in 1992. The psychological impact of infertility on men has been downstream of that diagnostic history ever since.There is a pattern to most writing on this subject. Men do not talk about it, the story goes, because men process things differently. The history... Read more...
Why the Stone Stack Matters More Than Heater Wattage in the Sauna
Finnish sauna builders plan the stone mass before they pick a heater. A traditional wood-fired sauna carries 80 to 120 kilograms of rock. A standard residential electric sauna heater ships with 20 kilograms of stones and a picture in the manual showing loose stacking. Those two setups do not produce the same heat. The difference shows up in your heart rate and in how long you can stay in the room. The heater generates the heat. The stones decide what that heat feels like and where it lands.If you have... Read more...
Marijuana and Sperm: The Dose Question Nobody Measured
In 2019, researchers at Harvard followed 662 men through a fertility clinic and found two things that should not both be true. Men who had ever smoked had higher sperm concentrations than men who never had. Men who were smoking two or more times a week at the time of the study had lower concentrations. Same data set. Same paper. Opposite conclusions depending on how you slice the word "use."The paper, led by Nassan and colleagues and published in Human Reproduction, did something most earlier research never bothered to do.... Read more...
Shift Work Gave Us the Strongest Sleep and Sperm Data
In 2011, two researchers at the University of Chicago paid ten healthy young men to sleep five hours a night for one week. Eve Van Cauter and Rachel Leproult were not measuring sperm. They were tracking daytime testosterone. By day five, levels had fallen 10 to 15 percent. The study ran in JAMA. The detail most men gloss over is that five hours a night was the entire intervention. No all-nighters, no rotating shifts, no added stress. Five hours a night sounds like a manageable Tuesday.The jump from testosterone to... Read more...