The perfection of clocks and the invention of watches have something to do with modern nervousness, since they compel us to be on time, and excite the habit of looking to see the exact moment, so as not to be late for trains or appointments.
Before the general use of these instruments of precision in time, there was a wider margin for all appointments.
We are under constant strain, mostly unconscious, often times in sleeping as well as in waking hours, to get somewhere or do something at some definite moment.