Yes, feeling sad is one possible symptom of depression. Other symptoms of depression include a loss of interest in things you previously enjoyed, weight gain or loss, sleep problems, thoughts of death and suicide, restlessness, feeling slowed down, feelings of guilt or worthlessness, and difficulty thinking or concentrating.
But does feeling sad automatically mean that you do have depression? Not necessarily. Feeling sad can be a normal reaction to life events, such as a marital breakup or the death of a loved one. The difference between ordinary sadness and depression lies in its persistence and the effect it has on your day-to-day life. With normal sadness, you may feel sad, but you are able to cope with it and keep up with your daily life until eventually, the sadness lessens. When sadness lingers and becomes unmanageable, however, you may need to seek outside assistance for depression.
If you are experiencing some of the other symptoms mentioned above and your feelings of sadness have been around for longer than a couple of weeks, you may wish to talk with your family doctor about your sadness. Your doctor can first rule out or treat any medical conditions -- for example, hypothyroidism - which can cause symptoms of depression. Once these conditions are ruled out, your doctor will be able to either treat you for depression or refer you to a psychiatrist or therapist who can help you.
If you would like to learn more about the symptoms of depression, try taking our free depression symptoms screening test to see which depression symptoms apply to you.