The dataset used for the psychophysiological assessment of four patients with amyotrophic lateral sclerosis (ALS) at advanced stages of the diseases with no means of communication, referred to as complete locked-in syndrome (CLIS). These datasets contain electroencephalogram (EEG), electrooculography (EOG) and functional near-infrared spectroscopy (fNIRS) recordings. During a four-day visit, each patient was recorded performing the various passive and active experiments at a sensory, perceptual, and cognitive level. The dataset includes somatosensory evoked potentials (SEPs), auditory evoked potentials (AEPs), resting-state in two conditions while eyes are open and eyes closed, Brain-Computer Interface (BCI) communication attempt, and during sleep.