RIGHTEOUS = AWAKE AND WICKED = SLEEP

Therefore, the righteous (the children of the day) heed the warning of the shofar and are aroused and awake from spiritual slumber. However, the wicked (the children of the night) allow themselves to be hidden from the spiritual understanding and judgment of Rosh HaShanah / Yom Teruah. So, this day shall come upon them as a “thief in the night”.