GHRL and obstructive sleep apnea syndrome: In the OSA group, significant negative correlation was found between BMI and average median ghrelin level (−0.32, p = 0.03) and ghrelin levels at 23:00 (−0.41, p = 0.005) and at 01:00 (−0.40, p = 0.007), and also between WC and ghrelin levels at 23:00 (−0.36, p = 0.01) and at 01:00 (−0.37, p = 0.01).