Depression is a mood disorder that can affect individuals of any age. You don't necessarily need to be diagnosed with depression to feel depressed as human tend to go through difficult periods in their life and they can experience periods of depression. Someone experiencing depression may have the following symptoms: fatigue, low energy, low motivation, thoughts of suicide, engaging in self-harming behaviours, feelings of sadness, hopelessness, irritability, loss of interest in activities that you once found enjoyable, feelings of emptiness, sleeping issues, feelings of worthlessness, and changes in appetite.