Another widely reported key benefit of the sauna is increased insulin sensitivity. This is simply a measure of how efficiently your body reacts to insulin and its role in glucose management, with the opposite of sensitivity being insulin resistance, which leads to Type 2 diabetes. 

“Regular thermal therapy…has the potential to improve impaired insulin sensitivity,” says one NCBI report from 2008.

Cardiovascular and bone benefits 

Sauna sessions can provide “benefits analogous to aerobic training” exercise according to the same NCBI report. It suggests sauna bathing might offer – in medically controlled conditions – the benefits of a mild cardiovascular workout for patients with existing conditions such as heart disease that make regular aerobic exercise dangerous.

So, does that mean it’s also an alternative to exercise for fit people? A kind of non-moving aerobics…? The answer is: a bit.

Saunas do give cardiovascular benefits, but they won’t do anything for your muscles – and maintaining good muscle tone and mass is crucially important to guard against osteoporosis and falls in later life. You will also miss out on the broad protection against dementia gained from resistance training, however.

Where you do get the big exercise boost is from taking a sauna after a workout. The benefits – all supported by scientific research – are legion. 

As well as the cardiovascular and circulation action, you get better muscle recovery and growth. Increased muscle strength. Reduced inflammation. Enhanced endurance. Better flexibility. And it boosts the insulin sensitivity upside effect.

Really, you’d be mad not to.

This oft-mentioned sauna benefit has been studied since the 1980s, with the increased production of human growth hormone (HGH) stimulated by those previously mentioned heat stress proteins. This is a good thing, because HGH aids muscle growth and preserves bone mass – two things you very much want to look after as you get older, when production of HGH declines. 

Lower cortisol levels

Another often touted benefit of sauna use is lowering troublesome “stress” hormone, cortisol. 

So helpful when running from a sabre-tooth tiger, so harmful for hours in bad traffic and linked to so many detrimental health settings, from low immune response, to increased blood sugars and weight gain, cortisol levels can be lowered by regular sauna sessions.

How often, how long?

Even one sauna a week will give you the benefits of muscle and mental relaxation and better sleep. If you’re new to being a human baked potato, start slowly, with five-minute sessions and build up. Drink a glass of water (and shower) before you go in and stay on the lower level and not too close to the hot rocks. Never let yourself doze off inside.

Also cool down slowly. You may want to work up to the full icy plunge, but it’s never a good idea for people with heart conditions, or pregnant women. If you have uncontrolled high blood pressure or any kind of heart disease, consult your doctor before hitting the heat.

Stick to one heat assault at first, but as you become more experienced you can bob in and out for several 10-minute sessions. Rest afterwards and make sure you fully rehydrate.