With the goal to better understand the mechanisms underlying loss of consciousness during anaesthesia and natural sleep, I am working on a project investigating how auditory processing in humans changes across different behavioral states. We record scalp electroencephalogram (EEG), intracerebral EEG, local field potentials (LFPs) and neuronal firing in multiple brain regions of neurosurgical epilepsy patients as they go to sleep and as they are sedated for routine deplantation of electrodes serving for clinical monitoring. Throughout the recording sessions a variety of auditory stimuli are delivered intermittently. We examine how auditory responses at various levels (individual neurons, LFPs and intracranial EEGs), and at different locations across the brain, compare between different states. By that, we hope to elucidate state-dependent changes of auditory processing accompanying sleep and anaesthesia.