Rapid Eye Movement (REM) rebound on initial exposure to CPAP therapy: a systematic review and meta-analysis

Rapid Eye Movement (REM) rebound is a polysomnographic phenomenon where a substantial increase in REM sleep is noted in patients with untreated obstructive sleep apnea (OSA) when first undergoing continuous positive airway pressure (CPAP) titration. The objectives of this study are to determine: 1) the percentage of patients experiencing REM rebound during CPAP titrations, 2) to quantify the relative increase in REM sleep duration and 3) to identify if there are patient variables associated with REM rebound. Four databases (including PubMed/Medline) were systematically searched through March 12, 2017. Four hundred sixty-seven articles were screened, 58 were reviewed in full-text form and 14 studies met the criteria for inclusion in this review. Eleven of the fourteen studies noted a statistically significant increase in amount of REM sleep during the titration night, compared to baseline sleep study. Pre- and post-CPAP REM sleep duration percentage means ± standard deviations (M ± SD) in 1119 patients increased from 13.8 ± 8.2% to 20.0 ± 10.1%; random effects modeling demonstrated a mean difference of 7.86 (%) 95% CI 5.01, 10.70, p-value <0.00001, corresponding to a 57% relative increase in REM sleep duration. The standardized mean difference (SMD) is 0.90 95% CI 0.59, 1.22, representing a large magnitude of effect. In studies reporting REM rebound, the REM sleep duration increased by 57% during the first CPAP titration night compared to the baseline sleep study. The prevalence of REM rebound varied between 23 and 46%. A low amount of REM sleep on the diagnostic PSG predicted REM rebound.