Is not His saying (to Him be ascribed all praise) "slumber" sufficient instead of His saying "sleep," even though slumber is the precursor to sleep?

The best interpretation of the word "sinah" (سنة) in the verse: (Slumber overtakes Him not, nor sleep) is that it refers to the beginning of drowsiness in the head, which, if it reaches the heart, turns into sleep. The verse negates the specific (slumber) then the general (sleep) from Allah. Some believe that negating "sinah" does not negate "nawm" (sleep), because there are those who are not afflicted by "sinah" yet sleep deeply, and others who are afflicted by "sinah" at times other than sleep.