By Tânia Esteves for EFE

No one knows for certain the reason why human beings need several hours of sleep every day, but a Portuguese neuroscientist has discovered the protein responsible for the mechanism regulating sleep.

Diogo Pimentel, part of an Oxford University team studying the intricacies of sleep, is one of the lead authors of a paper recently published in “Nature” magazine studying the sleep mechanisms of fruit flies.

The team, led by the Austrian founder of the experimental approach known as optogenetics Gero Miesenböck, has found the mechanism used to “turn off” neurons and thus control sleep in insects, making it possible to “awaken” them at will.

“Brain cells tend to alternate between active states and completely inactive ones, which is what led us to formulate the hypothesis that this same mechanism regulates sleep,” Pimentel told EFE.

The neurotransmitter responsible for deactivating neurons is dopamine, which initiates a process dependent on a protein known as “Sandman” _ or “João Pestana” in Portuguese.

This protein is generally not present in the neurons’ membranes during sleep.

The name of the protein has a contradictory backstory, since João Pestana is a mythical figure in Portuguese folklore, frequently appearing throughout popular nursery rhymes and lullabies.

João Pestana arrives once someone is starting to fall asleep, when drowsiness sets in and the eyelids (“pestanas” in Portuguese) feel heavy.

Nonetheless, introducing this protein into fruit flies makes them stay awake during an extraordinary length of time, a conclusion Pimentel reached after studying 24 different neurons belonging to the short-lived bugs.

Fruit flies are commonly used in experiments due to the many similarities they share with humans when it comes to sleeping patterns.

They require roughly the same amount of sleep, preferably during nighttime, and they even take afternoon naps now and then, although there are further reasons why they constitute ideal guinea pigs for these types of scientific studies.

“Many sleep-regulating mechanisms had already been initially identified in flies, showing important similarities to human traits,” Pimentel said.

“The big advantage of flies is that their nervous systems are a little simpler than human ones; they are easier to understand and manipulate,” he added.

Now that it has described the process through which the brain “turns off” to start its placid slumber, Pimentel’s team is attempting to find out the exact workings of the opposite process.

“We want to understand the reverse process: how these brain cells are re-activated to impede sleep and which signals stemming from other brain regions are used to re-awaken the neurons,” the researcher explained.

Pimentel, who has been studying sleep for the past four years, said he believed this discovery could be very useful to humans, as well as clarify many of the unknowns currently baffling neuroscientists.

“Understanding this process in an exhaustive manner is the first step to then try to solve the sleep-related problems countless people suffer from, either because they cannot get enough sleep or because they sleep too much,” he said.

The scientist emphasized that the array of sleep dysfunctions affecting people’s well-being would be easier to grasp once the problems have been thoroughly studied.

“I think that, from a neuroscientific point of view, this remains one of the greatest enigmas that have yet to be solved, and deciphering it will be our next step,” he added.

Although the question of why we need to sleep continues to be a mystery, Pimentel predicted that the day sleep-regulating mechanisms are fully understood by the scientific community, researchers will finally be able to fully address this ancestral stickler.

Lisbon, Aug 27 (EFE)