The SDB-positive group had a higher mean of EPO levels on both days (day 1 mean, 24.3 ± 7.7; day 3 mean, 21.9 ± 4.0) compared to the EPO levels in the SDB negative group (day 1, 10.4 ± 3.2; day 3, 12.5 ± 3.4). Here, EPO is linked to sleep apnea syndrome.