
Fitness & Health
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Published 20:36 24 Apr 2016 BST

Sleep scientists call it the First-Night-Effect (FNE) and it has affected humans for years, but it was never fully understood before now.
The study, which can be read here, found that a person's brain had asymmetrical patterns of sleep activity with one half of the brain remaining active, although not fully alert, and reactive to outside stimulus.
This trait is also present in some animals such as dolphins and whales who are vulnerable when asleep and need to remain alert.
The scientists are hopeful that they can discover a way to shut off this trait now they know more about it, this could be of particular use to people who travel for work.
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