Phase-locked loop for precisely timed acoustic stimulation during sleep

Giovanni Santostasi, Roneil Malkani, Brady Riedner, Michele Bellesi, Giulio Tononi, Ken A. Paller, Phyllis C. Zee

Research output: Contribution to journalArticle (Academic Journal)peer-review

69 Citations (Scopus)


A brain–computer interface could potentially enhance the various benefits of sleep.

New method
We describe a strategy for enhancing slow-wave sleep (SWS) by stimulating the sleeping brain with periodic acoustic stimuli that produce resonance in the form of enhanced slow-wave activity in the electroencephalogram (EEG). The system delivers each acoustic stimulus at a particular phase of an electrophysiological rhythm using a phase-locked loop (PLL).

The PLL is computationally economical and well suited to follow and predict the temporal behavior of the EEG during slow-wave sleep.
Comparison with existing methods

Acoustic stimulation methods may be able to enhance SWS without the risks inherent in electrical stimulation or pharmacological methods. The PLL method differs from other acoustic stimulation methods that are based on detecting a single slow wave rather than modeling slow-wave activity over an extended period of time.

By providing real-time estimates of the phase of ongoing EEG oscillations, the PLL can rapidly adjust to physiological changes, thus opening up new possibilities to study brain dynamics during sleep. Future application of these methods hold promise for enhancing sleep quality and associated daytime behavior and improving physiologic function.
Original languageEnglish
JournalJournal of Neuroscience Methods
Early online date28 Nov 2015
Publication statusPublished - 1 Feb 2016


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