One clinical study of patients with unipolar or bipolar depression previously reported that a single 0.5 mg/kg infusion of IV ketamine may correlate with advances in circadian rhythm and increased levels of 24 h motor activity, as measured by wrist actigraphy.26 Ketamine is also known to rapidly induce expression of clock genes,27 which are responsible for regulating circadian cycles. The gene discussed is CLOCK; the disease is bipolar disorder.