BiLevel therapy device for the treatment of patients with obstructive, mixed, or complex sleep apnea and a high and/or fluctuating pressure requirement, poor CPAP compliance, central apneas, sleep-related or position-dependent hypoventilation (e.g., OHS), respiratory insufficiency, coprevalent respiratory insufficiency (e.g., COPD/ overlap). The device has different pressure levels during inspiration and expiration and a backup frequency for the treatment of central events.