The invention relates to a method and a device for the determination of the time characteristic of the breath depth (t) of a, in particular in the sleeping person, person. To individual acquisition instants are continuously height profiles (h) of the person (1) is produced. Height profiles of adjacent acquisition times are combined to form segments. The region of the abdomen - or chest region of the person in a function of the respective reference point or reference region (21) is selected as a viewing area (22). For each height profile (h) within the segment (s1, .., Sq) in each case is separately to the mean value of the distances between the inside of the viewing area (22) the points of the height profile (h) to a reference point or reference object is determined. For the segment (s1, .., Sq) , a signal (si) it is determined, which, for the respective time of taking the photograph (t1, .., tp) the height profile (h) of the for this height profile (h) is assigned to mean value determined. Based on the determined signal (si), in particular based on the signal amplitude, one or more, the temporal profile of the breath depth (t) values characterizing
