Continuous positive airway pressure (CPAP) is highly effective in treating obstructive sleep apnea (OSA), but adherence to therapy remains a major challenge. Despite its benefits in reducing daytime sleepiness and improving health outcomes, many patients do not use CPAP as prescribed. Adherence is defined as using the device for more than 4 hours per night, with 46–83% of OSA patients failing to meet this standard. Factors influencing adherence include patient perception of symptoms, improvement in sleepiness, and daily functioning, rather than disease severity. Behavioral interventions show promise in improving adherence, but few studies support their effectiveness. CPAP adherence patterns are established early in treatment and predict long-term use. Patients who skip nights of treatment tend to use the device for shorter durations, leading to increased daytime sleepiness and neurobehavioral deficits. The relationship between CPAP use duration and clinical outcomes is complex, with some studies suggesting that even low levels of use provide benefits. However, longer use is associated with better outcomes, including improved sleepiness, memory, and daily functioning. Predictors of CPAP use include nasal resistance, which can affect initial acceptance of treatment. Nasal surgery may improve adherence in patients with significant nasal resistance. Other factors, such as race and socioeconomic status, also influence adherence, though the exact mechanisms are not fully understood. Psychological factors, including patient perception of treatment benefits and self-efficacy, are important in determining adherence. Machine design and humidification have been explored as potential interventions to improve adherence. While heated humidification may reduce nasal symptoms, its effectiveness is not consistently supported by clinical trials. New CPAP modalities, such as bilevel and auto-CPAP, have been developed to improve comfort and adherence, but their benefits are not clearly established. Behavioral interventions, including cognitive behavioral therapy and patient education, have shown promise in improving adherence. These approaches, when implemented early in treatment, can lead to better outcomes and reduced dropout rates. Future research should focus on patient-specific factors and the integration of behavioral strategies into routine clinical practice. Overall, improving adherence to CPAP is crucial for achieving optimal clinical outcomes in patients with OSA.Continuous positive airway pressure (CPAP) is highly effective in treating obstructive sleep apnea (OSA), but adherence to therapy remains a major challenge. Despite its benefits in reducing daytime sleepiness and improving health outcomes, many patients do not use CPAP as prescribed. Adherence is defined as using the device for more than 4 hours per night, with 46–83% of OSA patients failing to meet this standard. Factors influencing adherence include patient perception of symptoms, improvement in sleepiness, and daily functioning, rather than disease severity. Behavioral interventions show promise in improving adherence, but few studies support their effectiveness. CPAP adherence patterns are established early in treatment and predict long-term use. Patients who skip nights of treatment tend to use the device for shorter durations, leading to increased daytime sleepiness and neurobehavioral deficits. The relationship between CPAP use duration and clinical outcomes is complex, with some studies suggesting that even low levels of use provide benefits. However, longer use is associated with better outcomes, including improved sleepiness, memory, and daily functioning. Predictors of CPAP use include nasal resistance, which can affect initial acceptance of treatment. Nasal surgery may improve adherence in patients with significant nasal resistance. Other factors, such as race and socioeconomic status, also influence adherence, though the exact mechanisms are not fully understood. Psychological factors, including patient perception of treatment benefits and self-efficacy, are important in determining adherence. Machine design and humidification have been explored as potential interventions to improve adherence. While heated humidification may reduce nasal symptoms, its effectiveness is not consistently supported by clinical trials. New CPAP modalities, such as bilevel and auto-CPAP, have been developed to improve comfort and adherence, but their benefits are not clearly established. Behavioral interventions, including cognitive behavioral therapy and patient education, have shown promise in improving adherence. These approaches, when implemented early in treatment, can lead to better outcomes and reduced dropout rates. Future research should focus on patient-specific factors and the integration of behavioral strategies into routine clinical practice. Overall, improving adherence to CPAP is crucial for achieving optimal clinical outcomes in patients with OSA.