But there's still one thing about summer that doesn't need to disappear that might surprise you. If you're not ready to let the heat go, then you can keep it going with sauna. There is a Finnish word I particularly like here: löyly.
Summer is slipping away. The evenings are starting to draw in. But there's still one thing about summer that doesn't need to disappear that might surprise you.
The heat!!
If you're not ready to let the heat go, then you can keep it going with sauna.
There is a Finnish word I particularly like here: löyly. Technically it describes the steam created when water hits the heated sauna stones, but it also captures something about the sauna feeling less like a room and more like an experience.
And there is good reason to keep seeking out that heat as the weather cools. Let’s dive in...
Where insight becomes impact
What I’ve been looking at this week…
Let’s start with sweat, because I think we underestimate it. We spend a lot of time trying to prevent sweating, disguise it and deodorise it. Here’s something interesting: freshly produced sweat is essentially odourless. Much of the smell we associate with sweating is created when bacteria living on the skin metabolise components of our skin secretions.
Deodorants deserve their own memo, by the way. There is more to that story than most people realise, so I’m saving that one for another week. For today, I want you to look at sweat differently.
Why do you sweat in the first place? Because your body is constantly trying to maintain homeostasis, the narrow internal balance that keeps your cells, enzymes and organs functioning properly.
Temperature is a big part of that. Your core temperature needs to stay close to 37°C because even relatively small shifts can affect how efficiently proteins, enzymes, the brain and cardiovascular system work.
When your temperature starts to rise, the hypothalamus in your brain acts like a biological thermostat. It increases blood flow to the skin and switches on millions of sweat glands. As sweat evaporates, it carries heat away and helps pull your temperature back towards its normal range. Sweating is one of the ways your body protects its internal environment from the heat outside.
Here's 5 more important reasons we S.W.E.A.T. S: Skin Regular sauna use has been associated with better skin hydration, more stable barrier function and faster recovery of skin pH. In a controlled study of 41 healthy adults, regular sauna users showed improved water-holding capacity in the outer layer of the skin. PMID: 18525205. If your skin tends to feel dry or dull, regular heat exposure may be paradoxically beneficial for you.
W: Workout Heat gives your heart work to do. Blood vessels dilate, blood flow to the skin rises and your heart rate increases as your body tries to lose heat. Finnish sauna currently has the strongest body of evidence among passive heat therapies for cardiovascular health. In Finnish sauna studies, people using sauna more frequently have lower rates of high blood pressure, stroke and fatal cardiovascular events. In one 20-year study, sauna 4 to 7 times a week was associated with a 63% lower risk of sudden cardiac death compared with once a week. PMIDs: 25705824, 28633297, 29720543. A sauna is one way to give your heart a workout without moving.
E: Excretion Sweat carries more than water and salt. A systematic review of 24 studies found arsenic, cadmium, lead and mercury in sweat, That's why when I test for heavy metals and detect these, I create a sauna protocol for my patients and monitor the changes. PMID: 22505948.
A: Adaptation Repeated heat exposure trains your body to cope better with heat. That is useful resilience, especially as heatwaves become more common and thermoregulation becomes less efficient with age. In a crossover study, sauna, hot-water immersion and exercise in the heat all produced heat- acclimation changes. PMID: 34957632. If the first hot day of summer affects you but two weeks later the same temperature feels easier, you have already experienced heat adaptation.
T: Tension Sauna also creates something many of us are short of: protected time to stop. A 2026 UK study involving 1,907 people found improvements in emotional wellbeing over time, with ritual and social connection contributing to the sauna experience. PMID: 41679164. If you find it almost impossible to sit still without reaching for your phone, sauna gives you a very practical way to practise stopping.
Track it to hack it.
What I’ve been monitoring this week…
If your goal is a meaningful passive heat stimulus to support heart health, detoxification and resilience, I look for three things: heat, sweat and recovery.
The exciting part is that there are now several ways to do this.
Traditional Finnish sauna has the deepest evidence base and still sets the benchmark for me. Temperatures typically sit around 80 to 100°C, with relatively low humidity until water hits the stones and creates löyly. That combination of heat, steam and ritual is powerful, and helps explain why Finnish sauna has such a strong place in the research.
Infrared sauna offers a different experience. The air temperature is usually lower, often around 45 to 65°C, which many people find more comfortable, while infrared energy heats the body more directly. In one recent study, 45 minutes of far-infrared sauna at 65°C raised core temperature by around 1.4°C in healthy adults, showing that lower air temperatures can still create a substantial thermal challenge.
And here is what I find particularly exciting: you can now bring sauna into your home with a dedicated cabin, or go smaller.
Infrared blankets wrap around most of the body, domes let you lie beneath an infrared heat source, and heated mats offer an even simpler way to bring heat therapy into a home or recovery space. They take up less room, make regular use easier and lower the barrier to consistency.
The best option is the one that gets you hot enough to create a physiological response, makes you sweat, allows you to recover well and fits easily enough into your life that you will actually use it.
From knowing to doing.
What this means for YOU…
The questions I'm most often asked about sauna are how hot, how long and how often?
Here’s the useful thing to understand first: the temperature on the sauna wall is the input. The rise in your internal body temperature is the physiological dose.
Two people can sit in the same 80°C sauna and absorb very different amounts of heat. Body size, hydration, heat acclimation, airflow, humidity and how long you stay in all change your response.
Studies demonstrate this beautifully. In one recent experiment, three 10-minute rounds in a traditional sauna at 80°C raised core temperature by around 0.4°C. Far-infrared sauna at 45 to 65°C for 45 minutes produced very little core-temperature change in that particular study. Yet a separate 2026 study using far-infrared at a constant 65°C for 45 minutes raised core temperature by 1.4°C. Same broad category of device, very different internal heat dose. PMIDs: 40332494, 42533687.
The ambient temperature alone cannot tell you how much heat your body has received. My practical sauna protocol If you are starting: 70 to 80°C for 10 to 15 minutes, 2 to 3 times a week. Give yourself a couple of weeks to become accustomed to the heat. Once you are comfortable: Aim towards 15 to 20 minutes, 3 to 4 times a week, usually around 75 to 85°C in a traditional Finnish sauna. That sits close to several research protocols. A Finnish study using 30 minutes at 73°C produced an immediate fall in systolic blood pressure from 137 to 130 mmHg and reduced arterial stiffness. Another randomised trial added just 15 minutes of Finnish sauna after exercise, three times a week for eight weeks and saw greater improvements in cardiorespiratory fitness, systolic blood pressure and cholesterol than exercise alone. PMIDs: 29269746, 35785965.
For longer-term cardiovascular associations, the famous Finnish cohort found the lowest risks using sauna 4 to 7 times each week, and sessions lasting more than 19 minutes were associated with lower sudden cardiac death risk than sessions under 11 minutes. This was observational research, so I use it as a guide to dose rather than proof of causation. PMID: 25705824.
What about infrared? Because infrared usually operates at a lower air temperature, sessions tend to be longer. Around 30 to 45 minutes is common in research, depending on the device and temperature. Judge your response by more than the temperature and timing display: are you becoming thoroughly warm, producing sustained sweat, seeing your heart rate rise and then recovering comfortably afterwards? That is a much better indication that your body has actually received a heat stimulus. And remember the three things I’m looking for: Heat. Sweat. Recovery. You want enough heat to create a response, enough duration to sustain it, and enough recovery that you want to come back and do it again.
CASE IN POINT 👜 One of my patients had advanced testing with me that unexpectedly showed a raised arsenic level. My first focus was to consider sources of exposure. With arsenic, I want to understand where it might be coming from, including water, rice, seafood or even traces from supplements. Once I had addressed the potential source, I wanted to support her routes of elimination. Hydration, bowel regularity and nutritional status were part of the plan, and I also added deliberate sweating through regular sauna, particularly after exercise. Why after exercise? Because there is some evidence that exercise-induced sweat can contain higher concentrations of arsenic and several other metals than sweat produced by passive heating alone. PMID: 35410004. Her heat protocol was Finnish sauna at 80 degress for 20 minutes alternate days, alongside good hydration and replacement of the minerals being lost through sweat. When I repeated her testing 3 months later, her arsenic levels had significantly reduced
That is the part of personalised medicine I love. A test identifies something you cannot feel, you look for the source, put a targeted strategy around it, and then measure again to see whether the biology has moved. Sauna was one part of that strategy, and in her case it gave deliberate sweating a very specific purpose.
🎯 If you'd like to make decisions with precision based on your personal data and using devices that are specific for you, then book a private consultation and let's start to decode your health.
Where you’ll find me…
Last week Prepping to speak at Ideas Fest! Really looking forward to this. It's Glastonbury for Entrepreneurs and Founders! Come and catch me on Wednesday 9th September at 10am on the Think Tank stage. I'm talking about what not to sacrifice on your way to success!
This week A big week for me as my brain-health work begins. I’m very excited to start putting even more emphasis on measuring and protecting brain health earlier. And a beautiful location in Knightsbridge launching later this week. All very exciting!
A thought to pause on… “Heat. Sweat. Adapt. Repeat.” Summer might be slipping away. But you can still keep the heat.
Wishing you a wonderful week ahead (that's 168 hours of your Million Hour life!! Dr Alka
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Take the free LQThis article is general education, not medical advice, and reading it does not create a doctor-patient relationship. If something has been going on for a while, please get it properly looked at by your own doctor.