Image copyright University of Colorado Boulder Image caption The researchers dragged volunteers on to a camping trip in the midst of a Colorado winter

Spending a weekend out camping resets the clock inside our bodies that influences sleeping habits, scientists at a US university have discovered.

The team argue that time in the great outdoors could help those struggling to get up in the morning and boost health.

The researchers said swapping bricks and mortar for canvas was not a long-term solution.

But exposing ourselves to more bright light in the day (and less at night) could help.

Our body has a daily "circadian" rhythm that anticipates day and night to co-ordinate how our body works.

It alters alertness, mood, physical strength, when we need to sleep and even the risk of a heart attack as part of a 24-hour cycle.

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'Arrogance' of ignoring need for sleep

Light helps the clock keep time, but modern life with artificial light, alarm clocks and smartphones has altered our sleeping habits.

The report is published in Current Biology and Dr Kenneth Wright, from the University of Colorado Boulder, told the BBC: "We're waking up at a time when our circadian clock says we should still be asleep."

He says this is damaging to health with studies suggesting links with mood disorders, type 2 diabetes and obesity.

And it also simply makes us really groggy and sleepy when we try to get up in the morning.

Reset button

So Dr Wright organised a series of camping expeditions for a small group of volunteers.

They had to wear special watches that recorded light levels and had blood tests to analyse the sleep hormone melatonin.

And the only artificial light they were allowed was the glow of a campfire, even a torch was banned.

Image copyright University of Colorado Boulder

The first thing they learned on a week-long camping trip in winter was people were exposed to 13 times more light than at home, even though it was the darkest part of the year.

Their melatonin levels also started to rise two-and-a-half hours earlier than before the expedition and they went to bed earlier too.

The campers were now sleeping and waking in tune with their body clocks.

Another camping trip showed most of that benefit could be gained by just going away for a weekend.

Dr Wright said: "We're not saying camping is the answer here, but we can introduce more natural light to modern life.

"It is something we as a society can regulate without people having to change behaviours."

He thinks homes, offices and schools could be designed to allow in more natural light.

And the new generation of "tuneable" light bulbs - that can be made far brighter in the day and dimmer at night - could also be used.

However, at the moment, people's body clocks would start to shift back to their old rhythm once the tent was packed up.

In order to continue to benefit from the camping reset, people would need to get a large hit of light in the day - for example by going out for a walk before work - and cut down in the evening by using less artificial light.

And if you want to watch your favourite TV show "record it", says Dr Wright.

Winter differences

The researchers also picked up clues that our body clocks alter during the year and that may affect how our body functions.

In a week of summer camping, melatonin production was altered by two hours, in winter it was altered by 2.6 hours.

It is a suggestion there is something different about the way our bodies react to the longer or shorter day.

And we already know that some people suffer from low mood with seasonal affective disorders.

Dr Wright added: "We have a hint there's something there and maybe at one point it time it was critical and now, in a modern environment, maybe we don't need to worry about putting on more weight in winter, but the impacts may still be hardwired in our physiology."

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