Historically, depression has been diagnosed more commonly in women than in men. This does not mean necessarily that males actually experience less depression—but they often experience depression differently than women. Since their symptoms and behaviors differ, males may not always recognize themselves (or be recognized by others) as being depressed. People with depressive illnesses do not all experience the same symptoms and the severity, frequency, and duration of symptoms vary depending on the individual and his or her particular illness. While women with depression are more likely to have feelings of sadness, worthlessness, and excessive guilt, men are more likely to be very tired, irritable, lose interest in once-pleasurable activities, and have difficulty sleeping. Substance abuse or dependence may co-exist with depression. Indeed, research shows that mood disorders and substance abuse commonly occur together. More tomorrow.