The science of sleep has been receiving a lot of attention in these past few years, and why not? Sleep is poorly understood, but thought to aid in memory-forming and other essential neurological activities.
German researchers recently experimented with applying gentle electric currents to sleeping subjects. In a study published in Neuron, the researchers played sounds (“pink noise”, a signal where the power per Hz is inversely proportional to the frequency) for their sleeping subjects while said subject were in deep sleep. While this did not cause subject to experience more deep sleep cycles, it did allow them to stay in deep sleep longer.
Subjects were also given a list of word pairs to memorize the night before. On nights were researchers played sounds, subjects did much better recalling their word lists (remembering 22, as opposed to 13).
The main thing that made sound simulation work in this case is that the frequency of the sounds were in sync with subject’s brain waves. It’ll be awhile before your doctor is prescribing sleep frequency therapy, but with researchers proposing brain simulation as a way of treating depression and other ailments, perhaps it’s not far off.