Spending just one week camping out in the natural light is enough to synch the circadian clocks with the timing of sunrise and sunset, a new study has revealed.

The study, by University of Colorado Boulder, found that the synchronization happened in that short period of time for all participants, regardless of whether they were early birds or night owls during their normal lives.

"What`s remarkable is how, when we`re exposed to natural sunlight, our clocks perfectly become in synch in less than a week to the solar day," CU-Boulder integrative physiology Professor Kenneth Wright, who led the study, said.

Electrical lighting, which became widely available in the 1930s, has affected our internal circadian clocks, which tell our bodies when to prepare for sleep and when to prepare for wakefulness.

The ability to flip a switch and flood a room with light allows humans to be exposed to light much later into the night than would be possible naturally.

Even when people are exposed to electrical lights during daylight hours, the intensity of indoor lighting is much less than sunlight and the color of electrical light also differs from natural light, which changes shade throughout the day.

The study is published online in the journal Current Biology.