〔Abstract〕 Abstract Objective To monitor changes in blood pressure during rapid eye movement ( REM) and non-REM (NREM) sleep in patients with obstructive sleep apnea (OSA) , and to analyze the effect of obstructive respiratory events on blood pressure during different sleep stages . Methods A cross-sectional trial was adopted on 1 219 pa- tients diagnosed with OSA in the Department of Otolaryngology of West China Fourth Hospital . The obstructive re- spiratory events and blood pressure of patients during REM and NREM sleep were monitored . Additionally , the symptoms of blood pressure fluctuations in OSA patients during different sleep periods and the effects of obstructive respiratory events on blood pressure fluctuations were analyzed . Results SBP and DBP during REM and NREM sleep both tended to rise as OSA worsened . The differences in SBP , DBP , mean apnea time ( MAT) , mean hy- poventilation time (MHT) , lowest oxygen saturation (LSpO2 ) , and oxygen desaturation index (ODI) in different sleep periods were statistically significant (P < 0. 05) . Multiple linear regression analysis revealed that SBP during REM sleep was negatively correlated with LSpO2 and the apnea-hypopnea index (AHI) (P < 0. 05) , but positively correlated with ODI(P < 0. 05) . DBP during REM sleep was negatively correlated with LSpO2 , AHI , and MHT(P < 0. 05) , but positively correlated with ODI(P < 0. 05) ; SBP and DBP during NREM sleep were negatively corre- lated with LSpO2 (P < 0. 05) . Conclusion As the severity of OSA increases , the blood pressure values during dif- ferent sleep periods rise accordingly. The blood pressure levels during REM sleep in OSA patients are higher than those during NREM sleep . LSpO2 is an important factor causing blood pressure changes in different sleep periods . AHI , ODI , and MHT are important factors causing blood pressure changes during REM sleep .