NPAS1 is a basic helix-loop-helix transcription factor. Npas1 is expressed in the developing forebrain in neuronal precursors of GABAergic projection neurons in the globus pallidus and basal forebrain as well as cortical and hippocampal interneurons. Experiments in mice have linked neurons expressing Npas1 in the external globus pallidus to motor control and those in the basal forebrain to sleep-wake control and stress responsiveness. Knockout and gene expression experiments have linked Npas1 to the control of behaviors and genes related to neuropsychiatric disorders