After a long day, sitting in a sauna can feel amazing, the heat relaxing your muscles and mind. But if you’re a man looking to start a family, you might wonder: could those steamy sessions be affecting your fertility? We realise just how important this subject is, and how rarely it’s talked about in the wider wellness world. So we’re stepping up to share what we’ve learned and support our community in the way we know best. We don’t claim to have all the answers, but we’re opening up the conversation to explore this area of men’s health together. In this article, we’ll look into what science knows about men’s fertility and saunas, share some expert insight from our consultant Earric Lee, and keep an open mind about what we don’t know. Think of this as an ongoing exploration, backed by research but rooted in human curiosity and experience. Whatever you take away from this, our advice is always please consult your health professional for advice about your fertility.

Heat and Sperm. What Do the Studies Say?

Let’s address the elephant in the hot room: high heat can impact sperm. Testes prefer cooler temperatures for optimal sperm production (there’s a reason they hang outside the body, to stay a few degrees cooler!). Prolonged heat in that area is known to impair sperm formation. Saunas, of course, are all about heat, so what does the evidence say about their effect on the “swimmers”?

In summary, yes, prolonged heat exposure does have an effect on spermatogenesis (the process of male sperm production). But it’s not that simple and the evidence is somewhat reassuring for those hoping to start a family.

There’s a lot of research out there so we needed some help filtering out the noise, so we spoke to an expert in the field, Earric Lee, PhD, lead scientist for the sauna research institute (SRI), postdoctoral researcher in cardiac rehabilitation, heat therapy, and sauna bathing to offer his insight.

Earric highlighted a significant study from 2013 that evidences that sauna exposure affects human spermatogenisis. Let’s get into the detail of the study:

Sauna protocol: 80–90°C for two sauna sessions of 15 min per week, for 3 months.
Sex hormones, sperm parameters, sperm chromatin structure, sperm apoptosis and expression of genes involved in heat stress and hypoxia were evaluated at the start, at the end of sauna exposure and after 3 and 6 months from sauna discontinuation in ten normozoospermic (describes a semen analysis result where all sperm parameters—including count, motility, and morphology—are within the normal range) volunteers. The study found a transient decrease in sperm count and progressive motility along with impaired mitochondrial function and sperm DNA packaging when compared with baseline (but no modification of sperm morphology and viability). However, after 6 months from the end of sauna sessions, semen
parameters returned to normal. Authors hypothesize that the reduction of sperm count observed after heat stress could be related to a less efficient spermatogenic process.

Study reference here.

So, the amount of time spent in a sauna over a period of time is significant. We dig a little further in another study from 2018:

During the first 2 weeks of sauna exposure, no semen alteration was recorded. However, after the third and fourth week, a slight but significant decrement of sperm viability was detected. In addition, sperm progressive motility, normal morphology and acrosome reaction (process where sperm release enzymes to penetrate the egg’s outer layers)  underwent a decline even from the third week of exposure (evaluated in 8 of 18 patients). Of note, after 2 months from the end of sauna sessions, sperm parameters were almost completely restored.

Study reference here.

But what about those of you who are sparing with their sauna use? Surely, limited heat exposure should be OK? Earric highlighted this article to help us understand a little better:

Single sauna session: 85 °C for 20 minutes

Semen was collected at weekly intervals for 3 weeks before and 10 weeks after the sauna exposure. The numbers, morphology, ultrastructure, motility, viability and metabolism of the sperm was assessed. Sperm numbers fell within one week and slowly returned to normal in 5 weeks. The earliest ultrastructural change was swelling of the plasma membrane, followed by an increase in the number of immature forms and disorganization of the arrangement of the mitochondria. Motility, glucose utilization and lactic acid accumulation of the sperm rose temporarily immediately after sauna.

So What are the Headlines?

Sperm Count Drops: After a period of regular sauna sessions, sperm counts and motility (movement) showed a decline from their baseline.

Quality Changes: It wasn’t just the number of sperm affected. The heat exposure also altered aspects of sperm quality – for example, the way DNA is packed in the sperm and their mitochondrial function (the sperm cell’s energy source) were impaired during the sauna period. These factors are important for healthy, fertile sperm. The good news is that these too seemed to recover after enough time away from heat.

Reversible Effect: In all studies, by six months after stopping the saunas, sperm counts had rebounded to normal levels. In other words, the negative impact on sperm production appeared to be reversible once the heat exposure was removed (it takes the body around two to three months to generate new sperm, so this timeframe makes sense.)

Hormones are Unaffected: Interestingly, the men’s reproductive hormone levels (like testosterone) did not change significantly during the experiment. So the sauna wasn’t lowering their testosterone, it was affecting fertility more directly at the level of sperm development (spermatogenesis).

Expert Advice: The studies conclude that scrotal hyperthermia (overheating the testes) from frequent saunas causes a “significant but reversible impairment” of sperm production. They even suggested that avoiding activities that heat the groin, like saunas or hot tubs, might be wise for men who are actively trying to conceive. In practical terms: if you’re seeking fertility, you may want to dial down the sauna habit for a while.

It’s important to note that every body is different and we should remain curious to how heat affects us on an individual level. However, the results align with the broader understanding that heat can be harmful to sperm.

So, no Saunas for Men if they’re trying to Conceive?

Not necessarily, but moderation and timing are key. You might consider taking a break from intense heat if you’re actively in a conception phase. Remember that new sperm take around 64 to 72 days to fully mature, so if you reduce heat exposure now, you’ll see the payoff in sperm quality a couple of months down the line. One thing you shouldn’t do is think of saunas as birth control, they are not reliable for that! The studies above don’t directly measure actual fertility or pregnancy rates, and lower count doesn’t mean zero chance. (In other words, don’t count on a sauna session to replace your condoms, it won’t.)

Crucially, keeping a balanced perspective is part of this exploration. The effect of heat is also dose-dependent, a short, infrequent sauna is likely far less impactful than daily marathon sessions. If anything, stress and overall health play a huge role in fertility, and saunas (in moderation) might help reduce stress. So, it’s all about balance. We asked Earric his take on the evidence and he suggests:

“If you do not plan on having any children in the near future, go crazy (knock yourself out). Otherwise, avoiding the sauna for 5 – 6 weeks before trying to conceive is the wise thing to do.”

Our take? Stay mindful and listen to the experts. If you’re planning to conceive soon, sounds like easing up on the super-hot soaks for a bit is recommended.

Staying Curious: The Journey Continues

As we wrap up this exploration, one thing is clear: the evidence is not finite, and we are remaining curious. Research has given us some valuable clues, like confirming that sauna heat can impair male fertility (at least temporarily). But there’s still so much we don’t know. Are some men more resilient to heat than others? Could regular sauna use have subtle long-term effects on fertility that we haven’t measured yet? And are there ways to get sauna benefits without the reproductive downsides (cooler saunas, shorter sessions, etc.)? These are questions begging for more research, and we’re keen to follow it as it emerges.

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