In 2013, Jan Born, a leading neuroscientist at the University of Tübingen in Germany, demonstrated that a certain type of noise, pink noise, has an impact on the slow oscillations of sleep, in other words on deep sleep. It is the result of a decade of neuroscience research on the stimulation of deep sleep. The first discovery in this field dates back to 2005 and the stimuli are then electric. It will take eight years, in 2013, to replicate it with a much more harmless element: sound.
Due to its natural sensitivity to noise, it is possible to influence the thalamus with sound stimuli. Pink noise is the preferred type of noise to influence the thalamus, thanks to its high spectral density which makes it more impactful.
Played at specific moments of deep sleep, these sound stimuli based on pink noise therefore have the effect of "boosting" the thalamus' impulses and optimizing their rhythm. This helps him synchronize more neurons at once, and more intensely. The result is an increase in the amplitude and density of slow waves, the main indicators of deep sleep quality.