If you want to experience lethargy and crabbiness by mid-morning go ahead and eat a piece of whole wheat bread with jam (jam and preserves do not qualify as a serving of fruit, it's pure sugar) for breakfast. (veganosity.com)
And even teen crabbiness is being tied to a lack of sleep. (challengesuccess.org)
In addition to the studies she cited linking good sleep habits as a protective factor against depression and extreme crabbiness, sleep helps the brain consolidate memories and learning, allows the body to process carbohydrates correctly (preventing excessive weight gain), benefits the immune and cardiovascular systems, and increases response time. (challengesuccess.org)