Since the Zeo is used as a REM detection device in the Sleeator 2 and its raw prefrontal EEG signal shows large eye artifact, these eye artifacts can be used for messaging from sleep world to wake world. Consequently, there is no extra device or connection necessary, since the same device as for REM detection is used for eye movement detection.
The process for training an eye signal detector is very similar to the REM detection process. However, instead of using the Fourier transform of the EEG signal, the raw signal itself should be used. Again, support vector machines, artificial neural networks, and a k-nearest neighbor classifier are available for detecting and decoding messages using eye movements.