Your brain is made up of a complex network of neurons and brain chemicals called neurotransmitters . Neurotransmitters carry messages from one neuron to another. Two of these neurotransmitters, norepinephrine and seratonin , are not produced in sufficient quantities in a depressed person's brain. Because of this, too few messages are transmitted between neurons, and the symptoms of depression occur. In clinical depression, the chemicals in the brain are just out of balance .
Any person can have occasional sadness, tiredness, or sleep problems.
What counts as clinical depression is that you or a loved one has symptoms nearly everyday, all day, for at least two weeks . These symptoms could include either a loss of interest in things you used to enjoy, or frequent feelings of sadness . There can be physical problems too, headaches , digestive problems , or sexual problems . Exam Room Network Users of this site are subject to our Privacy Policy , User Agreement and Terms and Conditions of Use . We subscribe to the HONcode principles of the Health On the Net Foundation .