As an antidote to one of the ills of modern life, it may leave some quite cold. When the lure of the TV or fiddling on the phone keep you up late at night, it is time to grab the tent and go camping.

The advice from scientists in the US follows a field study that found people fell asleep about two hours earlier than usual when they were denied access to their gadgets and electrical lighting and packed off to the mountains with a tent.

A weekend in the wilds of the Rocky Mountains in Colorado helped reset people’s internal clocks and reversed the tendency of artificial light to push bedtime late into the night. A spell outdoors, the researchers conclude, could be just the thing for victims of social jetlag who find themselves yawning all day long.

“Our modern environment has really changed the timing of our internal clocks, but also the timing of when we sleep relative to our clock,” said Kenneth Wright, director of the sleep and chronobiology lab at the University of Colorado in Boulder. “A weekend camping trip can reset the clock rapidly.”



To explore the sleep-altering effects of the natural environment, Wright sent five hardy colleagues, aged 21 to 39, on a six day camping trip to the Rocky Mountains one December. They left their torches and gadgets behind, and had only sunlight, moonlight and campfires for illumination.



The campers went to bed on average two and a half hours earlier than they did at home, and racked up nearly 10 hours of sleep per night compared with their usual seven and a half hours. Monitors showed that they were more active in the daytime and were exposed to light levels up to 13 times higher than they typically received at home.



Immediately after the trip, the campers returned to the lab where scientists measured the rise and fall of melatonin, the sleep hormone, in their bodies. Their melatonin began to rise – and so prepare the body for sleep – more than two and a half hours earlier than it did before the trip. “Even with a small number of people we saw robust effects,” Wright said. “It was the same in everyone. How our circadian clock responds to the natural light-dark cycle is part of our fundamental physiology.”



To see how quickly the natural environment could change people’s sleep patterns, Wright sent nine people, aged 19 to 37, on a weekend camping trip to the same mountains one July. This time they were allowed torches and headlamps. Another five people stayed at home for comparison.

Even at the height of summer, the weekend campers went to bed earlier than those who stayed at home. The effect was more pronounced at weekends, when those in modern housing with artificial lighting went to bed nearly two hours later than the campers. By spending the weekend outdoors, the campers were exposed to four times more light than the others, the scientists report in Current Biology.

But for those who view camping as voluntary punishment, Wright has good news. “We know we don’t have to go camping to achieve these benefits,” he said. “If our goal is to have people sleeping at reasonable times so they’re not asleep at work and school, there are things we can do in our daily lives. We would recommend getting more natural sunlight, and that could be starting the day with a walk outside, or bringing more light indoors if you can, or sitting by a window. As important, though, is to dim the lights at night,” he said.

Derk-Jan Dijk, director of the Sleep Lab at the University of Surrey, said that in such a small study it was hard to tease apart the effects of sunlight, outdoor temperature and other factors on sleep. But he added that the discussion about what artificial light is doing to our sleep timing and biological clocks is an important one.

“This should inspire people to look at all of the environmental factors that affect sleep rather than looking at the internal biological factors. There are some people who say ‘I can’t go to sleep early because I’m a late type, it’s in my genes’. But it’s exposure to artificial light that drives our clock later so we struggle to get out of bed in the morning.

“I don’t think the take home from this study should be ‘let’s go camping’. We should look carefully at the environment in our homes and our bedrooms, at the light and temperature in the evening, and see how that affects our decision to go to sleep,” Dijk said.