Concentrations of vascular endothelial growth factor (VEGF) and stromal cell–derived factor‐1 (SDF‐1) α proteins in murine blood plasma samples were determined by ELISA kits (mouse VEGF ELISA kit, R&D Systems, and mouse CXCL12/SDF‐1α Quantikine ELISA kit, respectively), according to manufacturer's instructions.18 (link) Plasma levels of VEGF and SDF‐1α in sham operation and at day 7 after HLI surgery were measured every 6 hours (6:00, 12:00, 18:00, and 24:00) in both the control and jet‐lag groups.