If the heart is vigilant (Song 5.2), then sleep is nothing for the body; this is like a person who is almost snoring and, when he hears robbers breaking in, does everything possible to escape them. Thus, if we are able to understand, we shall see that we are exactly like this.
“Other Old Man” John, Letters From The Desert: A Selection of Questions and Responses (St. Vladimir’s Seminary Press Popular Patristics Series)