The clinical characteristics of depression include behavioural, emotional and cognitive symptoms. Behavioural characteristics include loss of energy, disturbances with sleep and changes in appetite. Emotional characteristics include depressed mood, feelings of sadness, and feelings of worthlessness. Cognitive characteristics include a diminished ability to concentrate and difficulties with attention. In addition, cognitive characteristics also include focusing on the negative aspects of the situation, while ignoring the positives and in some cases thoughts of self-harm, death or suicide.