Obstructive sleep apnea (OSA) can occur in both rapid eye movement (REM) and non-REM sleep, but it is more prevalent in REM sleep due to the increased risk of upper airway collapse during this phase. REM OSA is more common in women and is often mild to moderate, with a higher prevalence in younger patients. Studies have shown that REM OSA is associated with systemic hypertension and excessive daytime sleepiness, similar to non-REM OSA. The duration and severity of respiratory events are typically longer and more desaturating in REM sleep compared to non-REM sleep. Continuous positive airway pressure (CPAP) treatment for REM OSA should be longer than 4 hours to cover the entire sleep period, but patients often show poor adherence. Alternative treatments, such as oral appliances, may be effective, but more research is needed. REM OSA is also linked to cardiometabolic risks, including increased carotid intima thickness and metabolic syndrome. The management of REM OSA remains challenging due to the need for prolonged CPAP treatment and the high rate of treatment interruption. Standardized definitions and better understanding of the pathophysiology of REM OSA are necessary to improve treatment outcomes.Obstructive sleep apnea (OSA) can occur in both rapid eye movement (REM) and non-REM sleep, but it is more prevalent in REM sleep due to the increased risk of upper airway collapse during this phase. REM OSA is more common in women and is often mild to moderate, with a higher prevalence in younger patients. Studies have shown that REM OSA is associated with systemic hypertension and excessive daytime sleepiness, similar to non-REM OSA. The duration and severity of respiratory events are typically longer and more desaturating in REM sleep compared to non-REM sleep. Continuous positive airway pressure (CPAP) treatment for REM OSA should be longer than 4 hours to cover the entire sleep period, but patients often show poor adherence. Alternative treatments, such as oral appliances, may be effective, but more research is needed. REM OSA is also linked to cardiometabolic risks, including increased carotid intima thickness and metabolic syndrome. The management of REM OSA remains challenging due to the need for prolonged CPAP treatment and the high rate of treatment interruption. Standardized definitions and better understanding of the pathophysiology of REM OSA are necessary to improve treatment outcomes.