Nicholas Rush suffering a nervous breakdown from caffeine (and nicotine) withdrawal after skipping dinner and not sleeping.
Caffeine withdrawal is a symptom which takes place when an individual is cut off from their daily caffeine intakes. The more caffeine those go without, the more severe the case. Those who suffer from the withdrawal would feel more stress and aggression. Since the Destiny expedition did not bring any coffee when they escaped Icarus Base, several people began suffering from this. One of them was Dr. Nicholas Rush, who seemed to be one of the more severe cases, since before Destiny, he drank several cups of coffee a day. Since he was also a Cigarette smoker, this was accompanied with Nicotine withdrawal. (SGU: "Darkness")