Auditory stimulation during non rapid eye movement (NREM) sleep has sparked remarkable interest for neuromodulation of sleep and improvement of memory and cognition. Yet, the electrophysiology of auditory brain responses in sleep remains elusive. Here, we studied auditory processing in the temporal lobe in humans using invasive electroencephalography recordings. We found that the auditory response hierarchy of wakefulness weakens during NREM sleep. NREM sleep instead exhibits two types of responses: (a) intracranial event-related potentials in the lateral and medial temporal lobe that are modulated by slow wave activity and are stronger and faster when sounds occur at or after the peak of local slow waves; (b) high-frequency responses in the temporal cortex, a proxy for neural firing, which are not affected by slow waves. These findings show slow wave resilient and slow wave dependent mechanisms for monitoring the environment during sleep and can drive future interventions based on auditory stimulation.
