Name: Hot baths.

Age: First used by the ancient Egyptians 4,000 years ago.

Appearance: A large thermoformed acrylic receptacle – or stone, if you’re an ancient Egyptian – filled with warm water.

Thank you for explaining what a bath looks like. I know. This is my job. You’re welcome.

More pertinently, why are you explaining baths? Oh, that’s easy. Because having a hot bath is exactly the same as doing exercise.

I mean, clearly it isn’t. Yes it is! The University of Coventry did a study, and discovered that having a bath is exactly the same as doing exercise.

Rubbish. Well, not quite. It found that hot baths can bring about certain similar health benefits to those of aerobic exercise. Heat therapies, including time in a hot tub, can raise core body temperature and improve blood flow, which can lower blood pressure, control blood sugar and reduce inflammation.

That isn’t the same as doing exercise. Well, no, you won’t build muscle or lose weight by having a bath, but …

Pfffft, I’m going to put my running shoes on. Wait! Imagine, for example, that you are old or have a chronic disease, and you’re unable to commit to regular exercise. If that’s the case, there is evidence that taking regular hot baths might be the next best thing.

Oh. I accept your apology.

How hot are we talking? This is the bad news. You probably can’t achieve these health benefits from your own bath. There is not much to be gained from plonking yourself in a tub that quickly loses heat during the episode of Bridgerton you’ve set aside for the occasion.

So what then? It’s better to sit in a hot tub. Charles James Steward, one of the study’s authors, recommends sitting up to your shoulders in a hot tub that is heated to approximately 40C (104F) for an hour.

Is that safe? As long as you’re willing to overlook the increased risk of dizziness, fainting and dehydration that comes from staying in a hot bath for that long.

What about saunas? Glad you asked. They broadly achieve the same thing. A study in Finland showed that middle-aged men who had four to seven sauna sessions a week enjoyed a 50% reduction in their risk of fatal cardiovascular disease compared with those who had only one sauna a week.

This is incredible. It is thought to be an antidepressant, too, and has been shown to decrease the risk of dementia.

Well, that’s it. I’m going to buy myself a hot tub and/or a sauna. That’s the spirit – although it’s worth remembering that exercise is generally better for you than just taking a bath, so maybe buy an exercise bike, too.

Do say: “Baths can make you healthier.”

Don’t say: “I’m running a marathon … from my hot tub.”