Why we sleep badly when we travel
A new study has shown that one half of the human brain remains on high alert the first time you sleep in a new place, a potential explanation for the poor sleep often reported by travellers.
Dr Chris Smith of The Naked Scientists told This Way Up's Simon Morton that this 'first-night effect' has been identified in human sleep research, and is regarded as a typical sleep disturbance. But until now nobody has really understood why it happens.
Now a paper in the journal Current Biology by Yuka Sasaki and her colleagues at Brown University has found that on the first night sleeping in a new location, the left hemispheres of a group of adult volunteers showed significantly different patterns of brainwaves compared with the opposite side of the brain or the left hemisphere on a subsequent night's sleep.
The researchers said that the results point to the conclusion "that troubled sleep in an unfamiliar environment is an act for survival over an unfamiliar and potentially dangerous environment by keeping one hemisphere partially more vigilant than the other hemisphere as a night watch, which wakes the sleeper up when unfamiliar external signals are detected."
Although the researchers only looked at the first phase of sleep, Dr Smith said that it always seemed to be the left hemisphere of the brain that played this role, reflecting the relative dominance of the left side of the brain in most people.
This could suggest that humans sleep like some animals, including birds and whales, that are known to rest one side of their brain at a time when they rest so that they can stay alert to danger.