No matter how much you love Christmas, wrapping up warm in winter woollens and those gorgeous, crisp autumn days, it’s difficult not to dread the lack of daylight this season brings.

And as the clocks go back, the nights are set to draw in even earlier: hello winter blues and, for many, the depression of seasonal affective disorder (SAD).

While it’s hard not to associate the diminishing daylight with a sense of gloom, it’s worth remembering that darkness also plays a crucial part in keeping us healthy.

Just as sunlight is vital for vitamin D production and more, we couldn’t do without a healthy dose of darkness either.

Here are some reasons why…

It regulates our body clock

As social creatures, we’ve come to rely on a framework for the day, regulating when we eat, work, rest and play (unless you work shifts, of course!). Sleeping at night isn’t just logical though – it’s important, and we’re biologically programmed to want to sleep when it’s dark.

“Darkness is an absolute prerequisite for good sleep,” says independent sleep expert Dr Neil Stanley. “Our bodies are designed to work according to light/dark cycles - in the morning, it takes just four minutes of daylight to tell our bodies it’s daytime. And at night-time, the minute it starts going dark, we begin to release the hormone melatonin, which is the signal to the body that it’s time to go to sleep.”

This regulation means our bodies routinely have enough time to regenerate and recharge, and keep us tip-top for action, physically and mentally, during waking hours.

It boosts our immune system

As we know, poor sleep doesn’t just make us feel groggy and less able to concentrate, it impacts our health both in the short and long-term. Lack of quality sleep (the proper, deep kind) is linked with a suppressed immune system, so if you’re sleeping badly and feeling run down, catching every cold going, that could be why.

Research has also found that melatonin plays a role in helping us fight cancer. In fact, studies have suggested that sleeping in total darkness may be a factor in preventing cancer, and also in the effectiveness of certain cancer treatments.

That all-important melatonin is at the centre of it all, and one of the best things we can do is ban screens from the bedroom!

The blue light from a computer or mobile phone can stop you sleeping

“We know from recent work that things like computers, TVs and mobile phones fluoresce in blue light, and blue light is what tells us it’s daytime,” explains Dr Stanley.

“Things that fluoresce blue actually stop the production of melatonin. So while it might be naturally dark [and you may have the big lights off], if you’re looking at a computer, TV or smartphone, you’re actually going to be stopping that melatonin. The advice is to get rid of the screens at least 45 minutes before lights out.”

It helps prevent obesity

Obesity rates are rising, and so too is our addiction to technology – and it seems the two things could be linked in countless ways. Not only because our reliance on TV and computer screens means we spend less time moving and more time sat on our bums, but also because melatonin could play a significant role in our metabolisms.

A study by London’s Institute of Cancer Research published earlier this year found women who sleep in bedrooms with enough light to see across the room at night have bigger waistlines.

The link was still apparent even when other factors – like how much exercise they do – were taken into account. It’s too early to fully explain the results, but a recent study by the University of Granada found melatonin injections helped reduced obesity and weight-related diabetes in rats. Scientists believe the principles apply to humans too, and that our increased use of melatonin-blocking screens could be contributing to our increasing weight.