10 Star Trek Questions That Always Confused You
2. Why Does A Starship Have A NightShift?
The night shift aboard a starship was so-named because, rather than following a typical day-to-night pattern, which doesn't exist in space, it described the period of time in which the crew conducted fewer tasks. While this could be changed on a whim, such as when the USS Excalibur was attacked by the Borg during the night shift, it generally preceded the so-called day shift.
Night shift was usually crewed by junior officers, though oftentimes the senior officers would be assigned to supervisory roles. Lt. Cmdr. Data often commanded the night shift on the Enterprise-D, as he had no need of sleep. On the other hand, Doctor Crusher often volunteered to do so as it gave her a chance to stretch her command skills from time to time.
A four-shift routine was instigated by Captain Jellico, though this was quickly removed once he left the ship. On Deep Space Nine, a four-shift rotation was far more successful, with Major Kira commenting that it allowed officers far more flexibility in their working hours. This, in turn, led to less fatigue on shift.
While there was no 'night' in space, these night shifts gave the various crews a little break in the day, Borg attacks notwithstanding.