A brain cooling system includes a gas delivery system and a cooling apparatus. The gas delivery system may include an apparatus for establishing a desired pressure and flow rate for gases to be inhaled by a subject and an interface element. The pressurization element may comprise a continuous positive airway pressure (CPAP) device. The interface element may include a breathing mask, such as a nasal non-invasive ventilation (NIV) mask, or a nostril occlusive nasal delivery device. Such a brain cooling system may be used to treat cerebral hypoperfusion, as may occur with a cerebral vascular accident (CVA), such as a stroke, a traumatic brain injury, or cardiac arrest, or with conditions that may lead to a CVA or to cerebral hypoperfusion. In a cerebral hypoperfusion treatment method, cooled respiratory gases, which may include an elevated amount of oxygen, may be introduced, under an elevated air pressure that exceeds a normal, physiologic air pressure generated as a subject inhales spontaneously, into the nasal cavity of the subject.