Objective:To investigate the effect of sleep in normobaric moderate hypoxia on erythropoietin,reticulocyte, red blood cell, and hemoglobin concentrations.Method:Twenty- six males age between 19 and 22 participated in this study (Body massindex, 22± 2 kg/m2 ; percent body fat, 12 ± 3 ; percent fat free mass, 59 ± 8 ;maximum oxygenconsumption, 51± 6 ml/kg/min :mean ± SD). There were divided into control and hypoxic group.Hypoxic group were slept in hypoxic tent for 9 days for 8 hours per day at target oxygen concentrationwith 15-16 percent. Blood sample were collected before (day 1) and on day 5 and day 10 in bothgroups. Compared the difference of erythropoietin, reticulocyte, red blood cell, and hemoglobinconcentrations in two groups.Results:Hemoglobin concentrations in hypoxic group was higher than control group in day 5(control: 14± 0.7 ; hypoxic : 14.5 ± 0.8, P= 0.02). There was no difference in erythropoietin,reticulocyte, red blood cell between two group. However, erythropoietin concentrations was increasedon day 5 in hypoxic group (15.0±9.5, P=0.02) and day 10 (13.4±9.3, P=0.05) compared with day1(11.6± 6.1) the level of hemoglobin concentration on day 5 was greater than day 1 (Day 1 : 14.1± 1.0 ; Day 5 : 14.5 ± 0.8, P= 0.01) red blood cell increased on day 5 with in hypoxic group (day 1 : 5.1± 0.6; day 5 : 5.3 ± 0.7, P= 0.01).Conclusion:Slept in a normobaric with low concentration around 16 percentage of oxygenand 2,164 meter above sea level for nine days induced increased in erythropoietin concentrations,hemoglobin, red blood cell ,however, there was no change in reticulocyte.
