SELPLG and obstructive sleep apnea syndrome: PSGL-1 levels did not differ between controls and OSA patients either in the evening or in the morning (494.0/46.9–802.1 U/ml vs. 452.5/254.2–1265.9 U/ml, p = 0.67 in the morning, and 480.2/41.3–1027.6 U/ml vs. 497.5/50.2–1054.7 U/ml, p = 0.70 in the evening in controls and OSA patients respectively).