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What is the phenomenon known as the "first night effect"?

A few years ago, researchers tried to explain a phenomenon that could affect everyone. Who has never experienced significant difficulty falling asleep in an unfamiliar place for the first time? It must be said that this first night can actually be synonymous with a sleepless night.

A complicated first night

A few weeks ago, we talked about the fact that even a small amount of light can disrupt sleep and, at the same time, affect health. If the factors that can alter the quality of sleep can be numerous, others can cause insomnia. This is particularly the case with sleeping in an unfamiliar place. We then speak of the first night effect . On a plane, at a friend's house or elsewhere, the first night(s) can indeed be very complicated. It is also not a question of comfort since this phenomenon can occur even if it is a question of a luxurious hotel room.

In 2016, a team from the school of psychology at the Georgia Institute of Technology (United States) published a study on the subject in the journal Current Biology. Researchers are interested in what happens in our brain during this or these first restless nights.

What is the phenomenon known as the  first night effect ?

An asymmetry of the two cerebral hemispheres

Scientists have revealed that during a first night in a new place, the cerebral hemispheres do not find sleep in the same way . However, these two hemispheres agree very well if you fall asleep in a familiar place. It is therefore a question of an asymmetry of the two hemispheres of the brain when the first night effect occurs. Indeed, the right side falls asleep normally, while the left sidemaintains a certain vigilance . This allows him to monitor this unfamiliar environment during the night. In other words, the brain remains on alert in case of danger.

As part of their work, the researchers used neuroimaging techniques in order to observe the brains of eleven participants. This made it possible to study how brain waves react to stimuli during sleep. However, the emission of different noises made it possible to discover that the left cerebral hemisphere was desynchronized . In addition, scientists have observed a faster reaction of this same hemisphere in order to wake up the body. In case of danger, the left hemisphere therefore takes care of giving the alert so that the individual can fight or flee.

According to scientists, after one or two nights, the brain can finally relax and rest after getting used to this new environment. However, other research suggests that the first night effect could spread over four consecutive nights .