Described herein are nasal devices, including nasal devices formed in layers having four or fewer layers. In some variations, the nasal devices include a single integrated layer from which the flap of the airflow resistor is formed as well as the base of the holdfast region. The nasal devices may include a single aligner or rim body on the side of the device facing the subject. The aligner may protect the airflow resistor, and may help center or position the nasal device. In some variations, these nasal devices may include a noise-reduction feature. Also described herein are systems, devices and methods for determining if a passive nasal respiratory device having an airflow resistor configured to inhibit exhalation more than inhalation has been worn by a subject, and thereby confirming compliance.