This document discusses, among other things, a system and method for providing diagnostic information from a closed loop neuromodulator, configured to provide sleep therapy for a patient, to a user or a polysomnograph (PSG). A first portion of the diagnostic information can be received at a diagnostic indicator register of the closed loop neuromodulator and an LED driver can be switched using the first portion of the diagnostic information. A second portion of the diagnostic information can be received at a PSG interface of the closed loop neuromodulator and provided to the PSG for display.