Depression is a mental disease and it effects the whole body
The persistent feeling of sadness or loss of interest that characterizes major depression can lead to a range of behavioral and physical symptoms. These may include changes in sleep, appetite, energy level, concentration, daily behavior, or self-esteem. Depression can also be associated with thoughts of suicide.
People may experience:
Mood: anxiety, apathy, general discontent, guilt, hopelessness, loss of interest, loss of interest or pleasure in activities, mood swings, or sadness
Sleep: early awakening, excess sleepiness, insomnia, or restless sleep
Whole body: excessive hunger, fatigue, loss of appetite, or restlessness
Behavioral: agitation, excessive crying, irritability, or social isolation
Cognitive: lack of concentration, slowness in activity, or thoughts of suicide
Weight: weight gain or weight loss
Also common: poor appetite or repeatedly going over thoughts