ABSTRACT
<p><b>OBJECTIVE</b>To understand the influence of different sleep stages on respiratory regulation in normal people.</p><p><b>METHODS</b>We measured ventilation (VE) and occlusion pressure (P0.1) responses to hyperoxia hypercapnia (deltaVE/deltaPaCO2, deltaP0.1/deltaPaCO2) and isocapnic hypoxia (deltaVE/deltaSaO2 and deltaP0.1/deltaSaO2) in eleven non-snoring healthy people during wakefulness and during non-rapid eye movement (NREM) I + II, NREM III+IV, and rapid eye movement (REM) sleep stages.</p><p><b>RESULTS</b>During NREM I + II and NREM III+IV, the normal subjects showed no significant decrease in P0.1, deltaP0.1/deltaSaO2 and deltaP0.1/deltaPaCO2 (P > 0.05), but deltaVE/ deltaSaO2 and deltaVE/ deltaPaCO2 decreased significantly (P < 0.05). During REM sleep, P0.1 maintained the level during wakefulness, but both hypoxic and hypercapnic responses decreased significantly (P < 0.05).</p><p><b>CONCLUSIONS</b>Sleep has significant influence on respiratory regulation in normal people. The respiratory drive (P0.1) in both NREM and REM sleep stages could maintain the awake level due to an effective compensation to the increase of upper airway resistance. The P0.1 responses to both hypoxia and hypercapnia decrease only in REM sleep stage, which is in consistent with the clinical phenomenon that sleep disordered breathing occurs in REM in normal people.</p>