After we found enhanced platelet clot formation at ZT8 in Per2loxP/loxP-PF4-CRE, we next exposed Per2loxP/loxP-PF4-CRE and PF4-CRE controls to in-situ myocardial ischemia and reperfusion injury at ZT8. The gene discussed is PF4; the disease is myocardial ischemia.