I didn’t know, when my son and I set off for our dawn run this morning, that we were working out in the spirit of Noel Edmonds. The TV presenter has stunned viewers of I’m a Celebrity with his rippling physique, apparently. He says it is the result of exercising in the dark while electronic pulses play. But is it really more effective to train in darkness than in light?

At 6.30am on Wednesday, Lesley Waldron, a fitness trainer, was having this very conversation with her Wild Country Woman exercise class at a park in Long Ashton, Somerset. Class-goers can struggle to sustain interest in winter but, Waldron says, “It can be amazing. You are more connected to yourself in the dark. We get dawn right at the end of class. The birds start singing. The sun is coming up. There’s magic in that moment.”

Waldron’s class also enjoys “the privacy element … They’re not worried about wobbly bottoms or red faces.”

“If you want to sweat or are pulling funny faces, no one can see you,” agrees Leo Savage, a personal trainer at Third Space in London. This might account for the boom in gym classes with dimmed lights; at Barry’s Bootcamp, they have deepened the red to get it right.

However, Matt Roberts, who has trained David Cameron, Mel C and Naomi Campbell, insists that “darkness doesn’t change the way your body works. There is no physical benefit to working out in the dark as opposed to the light.”

Having said that, he occasionally runs in the dark and enjoys “all the senses being on alert … Exercise is a mind game. If something makes you more focused, that’s great.”

Savage, for instance, who trained in the dark as a rugby player and now runs in the dark, finds darkness motivating. “It’s almost a case of: ‘I’m one step ahead of everyone else.’ When you go home, the light’s coming up, and you’ve smashed it while everyone else is still getting up. In the evening, you feel you’re squeezing the last out of the day.”

Plus there is great news for anyone in the UK who wants to try a dark workout: at this time of year, you don’t even need to get up early.