Sauna Enthusiasts, Beware? It's Not Just Tobacco That's Bad for Sperm — The Overlooked "9 Habits"

"Fertility is not just a woman's issue" —— Lifestyle habits for "sperm health" to reconsider in the New Year

The end of the year and New Year is a time when the momentum to rebuild one's life increases, with thoughts like "Let's get our bodies in shape next year" or "Let's think about family planning." Recently, the condition of men, particularly the quality of sperm (motility, morphology, DNA damage, etc.), has become a frequent topic of discussion.

The background includes accumulated research showing that smoking, alcohol consumption, lack of sleep, stress, obesity, and exposure to chemical substances such as plastic additives can affect semen parameters and reproductive functionPMC.

However, what's important is not to oversimplify with "do this and it's immediately bad," but to understand it in terms of **"accumulation" and "reversibility (the possibility of recovery)."** For example, even if sperm formation temporarily worsens due to high-temperature exposure (such as saunas), there are reports that it is reversiblePubMed. This makes it well-suited for forming new habits in the New Year.

Below, we will organize "nine habits that could negatively affect sperm," which are often debated on social media, with as much evidence and "temperature" as possible.

Nine habits that could negatively affect sperm —— The points are "heat, chemicals, and lifestyle rhythm"

Here, we list nine items focusing on those that are "surprisingly easy to overlook" (smoking, excessive drinking, lack of sleep, stress, lack of exercise, obesity, etc., which are generally known, are also closely related in terms of mechanisms)ExSeed Health.

1) Continuous exposure to heat (saunas, long baths, hot tubs, etc.)

The testes are designed to function at a slightly lower temperature than body temperature, and "overheating" the scrotum can be disadvantageous for sperm formation. Studies have reported significant (though reversible) deterioration in sperm parameters due to continuous sauna exposurePubMed.
→ The practical countermeasures include "reducing frequency," "avoiding consecutive days," and "avoiding long durations" as adjustments in "quantity."

2) Creating "moisture/temperature rise" with tight underwear/clothing

This is one of the most contentious topics on social media. It often turns into a war of attrition like "boxer vs. briefs," but the point is more about temperature than the tightness itself. Articles introducing reports from Harvard-affiliated research teams show that the relationship between tight underwear and semen parameters is a research subjectTechnology Networks. On the other hand, medical institution explanations suggest that the impact might be smallSpring Fertility.
→ Rather than "winning or losing," it's reasonable to lean towards "breathability and less tightness" even if only during fertility efforts.

3) Unawareness of plastic-derived chemicals (BPA, phthalates, parabens, etc.)

The potential negative impact of endocrine-disrupting chemicals (EDCs) on semen parameters and sperm DNA is repeatedly discussed in reviews (BPA, phthalates, parabens, etc.)PubMed. Recently, warnings about "plastic additives and sperm count decline" have been reported, and discussions on regulations are progressing beyond individual effortsThe Guardian.
→ Practically, prioritizing small-burden substitutions like "not heating hot items in plastic containers" and "increasing glass/stainless steel" is advisable.

4) Using daily products (strongly scented care products, etc.) "without checking ingredients"

"Chemicals potentially contained in personal care products" are organized as a point of discussion for sperm impact in the context of EDCsExSeed Health.
→ Leaning towards "unscented" and "simple ingredients" is a choice that can be made without increasing costs.

5) Underestimating household chemical exposure during cleaning, weeding, etc.

Detergents, solvents, and pesticides increase exposure depending on "concentration and frequency." Reviews of EDCs and environmental chemicals discuss the potential involvement of household/occupational exposure in reproductionScienceDirect.
→ Ventilation, gloves, not mixing, and reducing usage frequency are effective basic actions.

6) Long-duration cycling (pressure + heat)

"Isn't exercise supposed to be good?" can cause confusion, but cycling involves saddle pressure and local temperature. Explanations dealing with the possibility of long-duration cycling per week being related to semen parameters existBicycling. Recent review papers also discuss the relationshipCermin Dunia Kedokteran.
→ Instead of eliminating it, "saddle adjustment," "breaks," and "avoiding long continuous durations" are practical.

7) Choosing "fertility lubricants" carelessly

This is a subtle blind spot. It has been shown in multiple studies that general lubricants reduce sperm motility in vitro (in test tubes).PMC.
→ The idea of choosing "fertility-friendly (sperm-friendly)" is rational (though it's a separate issue whether it increases pregnancy rates).

8) Overindulging in caffeine (large amounts of energy drinks, cola, etc.)

The relationship between caffeine and semen parameters is not monolithic, but reports have linked **extremely high intake (e.g., >800mg/day)** with decreased sperm concentration and total countOUP Academic.
→ The chain of "caffeine to sleep → can't sleep → more caffeine" is actually painful.

9) Leaning too much towards processed meats and ultra-processed foods

Studies have reported a negative relationship between processed meat consumption and sperm morphologyPMC. Furthermore, the impact of "ultra-processed foods" on male hormones and reproduction has been a subject of research and reporting in recent yearsOUP Academic.
→ Instead of "banning everything," the direction of "reducing frequency" and "increasing fish and unprocessed foods" is sustainable.

But ultimately, what works best? —— The essential "foundation" cannot be ignored

The above nine items are mostly "blind spots," but the foundation is still essential.

• Smoking and excessive drinking: Reports show a relationship with semen parameters and sperm DNA damage, and the possibility of increased negative effects when combinedPMC

• Lack of sleep: Reports of lower motility, etc., in groups with shorter sleep durationsPubMed

• Stress: Studies dealing with the relationship between stress indicators and semen parametersScienceDirect

• Obesity: Meta-analysis examining the relationship between BMI and sperm countPMC

• Moderate exercise: Meta-analysis showing the relationship between physical activity and improved semen parametersPMC

In short, the foundation of "sleep, weight, preferences, exercise" is more effective than special hacks. On top of that, it's practical to fill in "overlooked" areas like heat, chemicals, lubricants, and daily products.

SNS reactions: "Is that true?" "Can you use heat as contraception?" —— Between critique and practicality

Topics like these gain traction on social media. The reason is simple: lifestyle habits are a theme that anyone can relate to.

"Can underwear really make a difference? Isn't that an urban legend?"

In Reddit discussions, the explanation that **"heat kills sperm but doesn't destroy the cells that produce them"** gains supportReddit, while there are also calm critiques like "everyone is making definitive statements with little evidence, and even experts have divided opinions"Reddit.

This temperature difference is typical of social media. People who want to see things in black and white clash with those who want to handle things in shades of gray on the same timeline.

"So can you use heat as contraception?" is a half-joke

Within the same thread, there are also joking responses like "Can