First Night Effect – Sleeping In A New Place Leaves Half Your Brain Alert


Most of us find it difficult to sleep in a new environment. Even after travelling for miles and feeling dog tired, we tend to still sleep lighter when we are not used to the place.

A study has revealed that half your brain stays alert and prepared for danger when you sleep in a new place. Tagged the first night effect, by the researchers from Brown University in Rhode Island, USA, the study helps us understand the science behind this phenomenon a little better.

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They found that the left hemisphere of the brain remained more active than network on the right side of the brain. The study published in the journal of Current Biology found that stimulating the left hemisphere, in this case by playing sounds into the right ears of 35 volunteers was more likely to wake them up than when those sounds were played into their left ears.

The more active side of the brain was seen specifically during deep sleep and when the researchers repeated the laboratory experiment on the second and third nights they found the left hemisphere could not be stimulated in the same way during deep sleep.

First Night Effect

All the above may sound like gibberish to us, but the researchers explained that the study showed that; “when we are in a novel environment, inter-hemispheric asymmetry occurs in regional slow-wave activity, vigilance and responsiveness, as a night watch to protect ourselves”. Put in simpler terms, our brains remain partly alert so we can defend ourselves against any potential danger.

The first night effect researchers however remain in the dark as to whether the brain’s state lasts throughout the entire nights sleep as they only tested the first time a person fell into deep sleep each night. The researchers believes this is the first time that the ‘first-night-effect’ of different brain states has been identified in humans.

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It has however been fingered in some animal species, the most common example of which are dolphins and other marine animals. They shut down only one hemisphere of the brain when they go to sleep. A previous study noted that dolphins always consciously control their breathing. Without keeping the brain active while they sleep would probably drown.

So when you find yourself in a new environment and you are unable to sleep properly, it’s the first night effect, your brain is simply being conscious of the fact and attempting to stay alert, so no harm can come to you.