The thalamic reticular nucleus (TRN) is a critical brain region that greatly influences vital neurobehavioral processes, including executive functioning and the generation of sleep rhythms. Recently, TRN dysfunction was suggested to underlie hyperactivity, attention deficits, and sleep disturbances observed across various devastating neurodevelopmental disorders, including autism, schizophrenia and attention-deficit/hyperactivity disorder (ADHD). Notably, a highly specialized sarco- endoplasmic reticulum calcium (Ca 2+ ) ATPase 2 (SERCA2)-dependent Ca 2+ signaling network operates in the dendrites of TRN neurons to regulate their high-frequency bursting activity. Phospholamban (PLN) is a prominent regulator of the SERCA2 with an established role in maintaining Ca 2+ homeostasis in the heart; although the interaction of PLN with SERCA2 has been largely regarded as cardiac-specific, our findings challenge this view and suggest that the role of PLN extends beyond the cardiovascular system to impact brain function. Specifically, we found PLN to be expressed in the TRN neurons of the adult mouse brain and utilized global constitutive and innovative conditional genetic mouse models, in combination with 5-choice serial reaction time task (5-CSRTT) and electroencephalography (EEG)-based somnography to assess the role of PLN in regulating executive functioning and sleep, two complex behaviors that map onto thalamic reticular circuits. Overall, the results of the present study show that perturbed PLN function in the TRN results in aberrant thalamic reticular behavioral phenotypes in mice (i.e., hyperactivity, impulsivity and sleep deficits) and support a novel role for PLN as a critical regulator of the SERCA2 in the thalamic reticular neurocircuitry.