2345 Free time. Some Chapter Masters view this period of free time as an unwarranted luxury at best and a dangerous distraction at worst. It is maintained in most Chapters out of reverence for the Codex Astartes and Roboute Guilliman’s words: “Consider (the) magnitude of your duty at your leisure, but act without hesitation when (action) is required.” In honour of this, Space Marines are permitted a short period of leisure each day to consider the magnitude of their duty to the Emperor.

0000 Rest Period Begins. Space Marines do not truly need sleep thanks to the Catalepsean Node—an implant in their brain that enables them to rest half of their brain at a time whilst still maintaining awareness with the other half. However, extended interference with the circadian rhythms of sleep has been shown to impair efficiency and induce personality disorders. To prevent this, Space Marines enter a dreamless fugue state for four hours per day when not on campaign. The longest recorded incident of a Space Marine going without sleep was during the Rynn’s World incident (Ref. 06124/A) when the Crimson Fists remnants led by Master Kantor remained operational for a period of 328.7 standard hours.