Titus Livius (Livy), The History of Rome, Book 36
Evan T. Sage, PhD professor of latin and head of the department of classics in the University of Pittsburgh, Ed.

23. And the Romans for their part conducted the siege with engines rather than by personal combat; the Aetolians, on the contrary, defended themselves by arms. [2] For when the battering-rams shook the walls they did not, in the usual fashion, try to ward off the blows by catching the rams in nooses,¹ but made frequent armed sallies, and some carried firebrands also, to throw against the works. [3] There were also arches in the walls suitable for sally-ports, and they themselves, as they built new walls to replace those that were destroyed, left more numerous openings to permit sallies against the enemy in more directions. [4] In the early days, while they were fresh in strength, they did this both frequently and stoutly; day by day then their attacks grew fewer and more half-hearted. [5] For although many difficulties beset them, nothing wore [p. 229]them down so much as loss of sleep; the Romans,² with their wealth of men, sent relief after relief to the posts, while the Aetolians, on account of their small number, were tortured by constant toil falling to the same men day and night. [6] For four-and-twenty days, so that no time was free from fighting, against an enemy attacking from four sides at once, nightly toil was joined to daily labour. [7] When the consul saw that the Aetolians were now weary, judging both by the lapse of time and by the testimony of deserters, he formed the following plan. [8] At midnight he gave the signal for the recall, and withdrawing all his men from the works, until the third hour of the day he kept them quiet in camp; [9] then the siege was begun and continued again until midnight and then interrupted until the third hour of the day. [10] The Aetolians thought that the cause of interrupting operations was weariness, which had troubled them too, and when the recall was sounded for the Romans, as if they too were summoned, each for himself left his post, nor did they show themselves in arms on the walls until the third hour of the day.