For many thousands of years, says sleep expert Stephanie Romiszewski, humans had very different sleep patterns, tending to be much more dependent on natural light. “Before the industrial revolution,” she explains on the High Performance podcast, “we were much more in line with obviously the planet’s rotation and the seasonal changes.”

Around one in three people in the UK report some degree of insomnia, and Stephanie there are three key steps we can all take to get back to having a good night’s sleep – and we owe one of them, perhaps surprisingly, to the artificial light that most of us see as part of the problem.

Seize the day

Stephanie says that the first thing you should so is ensure that, no matter how much you fancy a lie-in, you get up at the same time every day.

“The key sleep mechanisms are your homeostatic sleep drive and that 24-hour cycle that you’re on. Whether you like it or not, your sleep, that’s how it works. So what can you do? The first thing is that ‘get up’ time.”

She adds: “The act of lying in actually perpetuates the problem because your body doesn’t know that you’re awake, essentially. Even if you’re not sleeping, let’s just say you’re just lying there because you can’t be bothered to get up. You actually are reinforcing that idea, that horrible, lethargic inertia that we get where we say ‘Oh, I just don’t want to start my day’.”

Let the light in

Stephanie says that, perhaps surprisingly, artificial light can help fix disordered sleep: “The second thing is the most influential external sort of influence on that 24-hour cycle –  light. 

“Unfortunately, since the industrial revolution, we’re now sort of working at times where you don’t always have light. So what you’ve got to think now is ‘How can I add in light into my morning?’.

Getting the light on early is the one key thing you can do to get your sleeping back on track, Stephanie adds: “So what light does is it really helps remind your brain that you need to be awake. We’re diurnal creatures, not nocturnal. So what that means is, like plants, we really react to the light.”

Stephanie says that making sure you expose yourself to bright light as soon as you get up on gloomy winter mornings. While sunlight is better, artificial light will do the job just fine: “It’s not as good as natural, but we can’t help that now. We need to sometimes get artificial light.”

Forget the rules

The idea that we all need eight hours a night is a “myth,” Stephanie says, and very often people worry so much about not sleeping that it makes matters worse.

“Sometimes when you’re sick, you need more sleep,” she explains. “If we’re obsessed with this idea that we have to get eight hours and it has to be every single night, there would be no variability in that. You actually wouldn’t be able to recover very well.”

The “eight hours a night” rule  is “pretty much a myth,” she says. “Even if you are genetically an eight hour sleeper, there is absolutely no way in this life that you’re going to get it every night. So you don’t need to worry about that.”