"In conclusion, degraded mood, increased perception of task difficulty, lower concentration, and headache symptoms resulted from 1.36% dehydration in females."If being down a half-liter of fluid causes healthy young women's moods to sour, I wonder what it does to the moods of women over 23.
Update, February 27: There was a parallel study done in men, which I failed to report, but should have! (Thanks, Shaun.) It found that while dehydration affected women's moods more, it affected men's memory more:
Mild Dehydration Impairs Cognitive Performance And Mood Of Men, British Journal of Nutrition, November 2011
"In conclusion, mild dehydration without hyperthermia in men induced adverse changes in vigilance and working memory, and increased tension/anxiety and fatigue."