The characteristics and clinical significance of REM<10% in children with sleep-disordered breathing.

Objective: Fractional time in REM sleep <20% ('little REM sleep') is indicative of more severe sleep-disordered breathing (SDB) in adults. We examined if other REM% is predictive of more severe SDB in children.

Methods: In this retrospective study of 616 pediatric SDB patients, age, sex ratio, BMI, sleep efficiency, awakening frequency, sleep latency, apnea-hypopnea index (AHI), obstructive apnea index (OAI), and lowest oxygen pulse saturation (LSpO) were compared among groups stratified according to REM%: REM≥20%, REM<20%, 15% ≤ REM<20%, 10% ≤ REM<15%, and REM<10%. Correlations with AHI, OAI, LSpO, sleep efficiency, and awakening frequency were examined in REM<20% and REM<10% groups. Associations of these parameters with REM<10% were examined by single- and multifactor regression.

Results: Pediatric SDB patients with little REM sleep demonstrated poorer sleep quality than patients with REM≥20%, while patients with REM<10% also exhibited more severe SDB. Specifically, the REM<20% group exhibited higher number of awakenings and lower sleep efficiency than the REM≥20% group (both P ≤ 0.001), as did each REM%<20% subgroup (lower sleep efficiency: all P < 0.05; higher awakening frequency: all P < 0.001). Moreover, compared to the REM≥20% group, the REM<10% also exhibited higher AHI (P = 0.025) and lower LSpO (P = 0.019). In the REM<10% group, individual REM% was negatively correlated with AHI (r = -0.216, P = 0.031) and positively with LSpO (r = 0.2, P = 0.046). Multifactor logistic regression correcting for age and BMI identified AHI as an independent predictor of REM<10% (P = 0.012, OR = 1.016, 95% CI [1.004,1.029]).

Conclusion: REM% <10% is associated with poor sleep quality and SDB severity in children, suggesting that this threshold should define "little REM sleep" in pediatric patients.