A/N: Thank you for all the reviews, guys! This next chapter references events in 'Requiem for Methuselah'.

Tiredness

The average human adult needs 6-8 hours of sleep per 24 hours. Less than that over a prolonged period of time leads to lapses in judgment, delayed reaction time, and dangerous decisions.

In times of crisis, the chance for enough sleep went down. Ironically, it was also during these very times when everyone needed to be mentally and physiologically at the top of their game.

This was why it was important to establish sleep rotations, especially among the medical staff. It wouldn't do for a surgeon of all people to make the wrong cut because they were seeing double being so sleep-deprived. Sleep had to be more than a luxury.

Unfortunately, resources were in finite supply. When Rigelian Fever swept through the Enterprise, you had fewer healthy people able to man their stations. You had fewer nurses and doctors able to relieve the working ones so they could get some rest. Numbers were never in your favor, not in the beginning. Too many affected, too soon, with not enough resources to combat the illness or boost the healthy and that was how outbreaks became epidemics.

When Nurse Radner showed up for shift only 3 hours after McCoy had last seen her, shivering under her layers and swaying with deep bags under her eyes, McCoy had gone to Kirk and made it a priority that the ship drop everything and find somewhere where they could get ryetalyn.

His staff was down to a skeleton crew and there were simply not enough of them for long, or enough, breaks. McCoy himself could feel the effects starting to drag on him, and that was even more dangerous.

Sleep-deprivation lowered your immune system's response. It made you more vulnerable to getting sick.

So he was short-tempered when they found some ryetalyn on a remote planet run by an old man and a young women. There was no need for hiding the processed element from them. There was no time for whatever games the guy was setting up between Rayna and Kirk. It was an unusual adventure, for sure, and a priceless home, but McCoy was itching to see that key element for their antidote, and was in no mood for tricks.

After achieving their goal (at long last) there was still more work to do. There was mixing and distributing the antidote, the tracking of progress for each person on the mend, monitoring any new patients for signs of fever, and watching out for – heaven forbid – any mutations.

He wished he could help Kirk process his emotional pain with how things turned out with Rayna, but the captain was physically healthy and McCoy had other patients. He left that task in the hands of Spock of all people, he must have really been out of it, but they all had to work with what they had.

Then right when it was all wrapping up there was an Engineering accident which pooled the rest of their human resources into the life-saving surgery of a fried ensign.

So Kirk walked back into Sickbay, mind unusually clear, to check on how the antidote was proceeding right as an orderly wheeled the injured man into post-op. To Kirk's eyes, the orderly didn't look too well, and had a mask covering their nose and mouth. He narrowed his eyes. In what sense would McCoy have let a sick, albeit recovering, orderly that close to another vulnerable patient?

He crossed into the operating ward… and stopped.

Nurse Chapel was passed out on the biobed they had likely just finished cleaning and operating on. M'Benga was curled up in the corner like he had backed up, sat down, then slumped over. McCoy had made it to the computer terminal, then face-planted. Kirk walked over and saw a report half-dictated on screen, literally trailing off mid-sentence. He rested his hand on McCoy's arm. The doctor did not stir.

Auxiliary medical personnel, he concluded, even though the idea was still half-formed in his head. Trained officers from other departments to come help pick up the slack if they were ever hit like this again. He was sure McCoy had several thoughts on it they could discuss after he awakened.

"Mr. Spock," he paged softly from the other room. "Meet me in Sickbay… we have some friends to tuck in."