What symptom is characterized by fatigue and lack of energy in depression?

Lack of energy is a primary symptom associated with depression, often manifesting as persistent fatigue that isn't solely a result of exertion. This symptom can significantly impact a person's daily functioning and quality of life. In the context of depression, individuals may find themselves feeling drained and unable to engage in activities they once enjoyed. This pervasive sense of fatigue can occur even with adequate sleep, distinguishing it from temporary tiredness seen in other conditions.

In contrast, agitation refers to a state of restlessness and emotional turmoil, which, while it can occur in depression, is not synonymous with fatigue. Insomnia, although closely related to fatigue, specifically refers to difficulty sleeping rather than the generalized lack of energy. Cognitive impairment can indeed occur in depression, but it encompasses issues like trouble concentrating or making decisions rather than directly describing the sensation of fatigue or low energy itself. Therefore, the symptom that most accurately characterizes fatigue and lack of energy in the context of depression is, indeed, lack of energy.