How stressful is watching your team in the World Cup? Scientists tested me to find out

As kick-off approaches I start breathing into a device that looks like a child's spinning top to record how quickly I'm breathing and how much carbon dioxide I'm breathing out.

By this point I'm starting to look like an extra in a low-budget Star Wars parody – and we are definitely the pre-match entertainment in a pub which is now heaving.

But the gear should allow us to monitor how my body changes – second by second - over the course of the Croatia match.

And as the referee gets the game under way, I am buzzing.

"I think tonight is going to be a real humdinger and that's great for us," says Bailey.

"I want to see a stress response, excitement, emotional anxiety, fear, shouting, forgetting to breathe, perhaps breathing too much, all of the above."

The readings in the opening moments show my heart rate is around 54 beats per minute, and my blood pressure 115 over 75.

"Everything is relaxed, despite the fact there are about 500 people staring at you," Bailey jests.

He was right to predict a humdinger – it was a six-goal thriller with highs and lows.

We had early drama. A Kane penalty… a guaranteed goal surely… but no, it's saved… wait… the Croatia keeper had strayed off his line and the referee orders a retake… Kane places the ball down again… shoots… GOAL!!!

I, and the rest of the crowd, are cheering with joy. But then comes the disappointment as Croatia equalise, before we take the lead again only to squander it and go in at half time with the match evenly poised at 2-2. It's an emotional rollercoaster - and the perfect conditions for the experiment.

At half-time we assess how our fellow England fans' bodies are coping.

Ollie, 23, says his heart is going "50 times a second" and he might "keel over and die" from the stress, while Tim, 38, says he needs more England goals because "currently it's pretty bad for my health".

Beth, 27, is more chilled: "I see my friends, I have a shout at the TV, I have a beer".

Unlike most of the crowd here, we're doing the experiment sober in case the depressant effect of alcohol influences the results.

The second half is far calmer. England are dominant and tension turns to jubilation as we win 4-2.

Damian and I head outside to discuss the results in the unofficial "post-match analysis beer tent".

"Your physiology is performing beautifully," he tells me. "We see a stress response whenever something exciting happens".

The first goal of the match - Kane's penalty – is a good example.

My heart rate cruised through most of the match in the low to mid-50 beats per minute but "literally within half a second" of Kane scoring my heart rate rose to 69 beats per minute.

Blood pressure went up too and there was less carbon dioxide in the air I was breathing out suggesting I was "hyperventilating a little" says Bailey and that led to a "reduction in blood flow into the brain".

And my saliva tests show levels of the stress hormone cortisol went from a chilled out 4.19 nmol/L before the match to a slightly stressed 5.15 nmol/L at the final whistle.

Altogether this shows a classic stress response in the body. When we talk about stress we often think about "bad stress" from work or exams or juggling-a-billion-things-at-once.

But Bailey says you can have good stress too. From an evolutionary perspective "stress is what keeps us alive" by activating our flight-or-fight response.

Bailey says my readings are like a "mild form of exercise" - just without burning any calories.

"You are elevating things that I would interpret as good for you, and you're recovering very quickly".

So there you have it, watching England is good for my health, however, there is a but. The same won't be true for everyone.

I have a relatively low stress response that "is almost Special Forces... you really are a cool customer I must say", says Bailey.

"You keep yourself physically active, you keep yourself in good shape."