Graphic illustration of sleeping time after adjusting to natural sleep (as an example), drawn up by Dr. phil. Sembach in March 1934 (taken from: Hippokrates 4/1937).
Dr. Sembach summarizes his "Experiences with natural sleep" as follows (see also page 17): "In my case, I could determine the personal result of the conversion to natural time as an extraordinary strengthening of my health and improvement of my efficiency. The extreme improvement as experienced by the young Stöckmann did not occur in my case. Perhaps this is due to the difference in our ages. I was born in 1881.
I was able to determine that it is possible to practise natural time, even over lengthy periods as the insertion of a short period of sleep in the late afternoon is compatible with the demands of cultural and social life. I could not discern that the time of 11:20 p.m. was the limit of 'absolute' natural sleep. For sensitive and weak persons, among whom I apparently belong, the relative natural time from 7 p.m. to 2 a.m. is much superior to any other sleeping time. For a short period of sleep, a greater depth of sleep is necessary which, as stressed by Stöckmann, must be well prepared for by moving the evening meal to between 3 and 4 p.m. and allowing work to ebb away, depending on its difficulty, between 5 and 6 p.m."

Graph depicting sleeping times after adjusting to natural sleep