In certain aspects, the preproghrelin gene, but not the ghrelin receptor (GHS-R1a) is required for normal integration of thermoregulation and sleep in mice. Particular aspects provide methods for modulation of thermoregulation and other ghrelin-mediated conditions (e.g., reduction of appetite or food intake, reduction of body weight or treatment of obesity, reduction of body temperature or induction of hypothermia, etc.), comprising administration of an inhibitor of ghrelin expression, and including, e.g., siRNA inhibition for treatment of obesity and for modulation of thermoregulation (e.g., induction of hypothermia in surgical settings benefiting from same). Additionally provided are methods for reducing body temperature or induction of hypothermia, comprising administration to a mammalian subject in need thereof an amount of an anti-obestatin antibody agent sufficient to reduce body temperature or induce hypothermia. Further methods comprise administration of a ghrelin peptide antagonist.