Sitting in a car or in a train, watching the landscape go by, the minutes tick away and sleep slowly wins us over… A universal experience that has interested scientists since the 1970s. Whether in adults or children , all the studies are formal, the vibrations and the movements of the pendulum favor the drowsiness. But why ? This is what American researchers tried to understand by carrying out experiments … on the vinegar fly.
Difficult to rock fruit flies in mini-prams. Biologists preferred to place the insects 40 centimeters above a multitube vortex stirrer, a scientific device that looks like a large kitchen scale and produces vibrations. Close enough for the waves to be felt by the insects, far enough not to prevent them from flying.
After a first fleeting frenzy, the little animals no doubt wondering why the air was trembling around them, the flies reacted exactly like humans, by biting a snooze. First lesson of the study published in Cell Reports, sleep induced by vibrations would therefore be the result of habituation, of a form of repetition which soothes when we know all danger has been eliminated. A bit like once the excitement of the trip has passed, the succession of the road only causes monotony.
Hence the second logical result: constant and continuous vibrations would be more effective in falling asleep than intermittent agitation. In short, what all parents experience when they have to rock a baby for a long time, to avoid an immediate awakening when the enchanting oscillations stop.
Third result: this sleep is no less restorative than “normal” sleep, even if it takes place in a restless environment. The fruit flies awakened from their nap went to bed later, without showing any signs of fatigue. Better! Sleep “under vibrations” would be even deeper, because flies have more trouble getting out. Hard for humans to believe … Anyone who has ever dozed off on the train will recognize that it only takes the cry of a child to wake up, and that the position guarantees more stiff necks, back pain and ants in them. legs that a comfortable recovery.
Identify neural mechanisms
Next, the researchers want to identify the neural mechanisms involved in the process, still using the fly’s brain as a model. This research also aims to find out whether this lulled sleep plays a role in memory, like “normal” sleep, and whether other repeated stimuli – for example the same scrolling image – also promote drowsiness.
Which might finally explain why the children stubbornly refuse to fall asleep on the road to vacation, only to nod ten minutes before arriving home. They just recognize the neighborhood, usually monotonous.