Electroencephalography (EEG) activity recorded with intracranial electrodes shares many characteristics with scalp EEG. Thus, physiological rhythms of wakefulness and sleep recorded with scalp EEG are detected, such as alpha activity, mu rhythm, sleep spindles, or saw-tooth waves. These activities exhibit some local specificities in the intracranial EEG (ICEEG). This chapter provides a description of physiological activity throughout the sleep–wake cycle, regarding both spectral particularities and specific rhythms, inside and beyond the Berger frequency band. Intracranial recordings including investigation of mesio-temporal structures during sleep have provided evidence that within and across area coupling of sleep oscillations support cognitive functions of sleep. However, several fields remain incompletely explored, and could benefit from larger database analysis, which could allow overcoming the spatial sampling bias of SEEG, and translational approaches, especially regarding subcortical structures recordings in movement disorders, simultaneous multimodal explorations including functional imaging, and age-specific investigation of maturational aspects of sleep.