Teens can be moody or occasionally melancholy. They may often shut down around adults or isolate by seeking comfort in texting or computer games. However they may also be depressed. If a parent suspects this may be the case, they should take their child to a doctor for an assessment.

Here are the symptoms to look for:

Depression

Sadness or hopelessness Irritability, anger, or hostility Tearfulness or frequent crying Withdrawal from friends and family Loss of interest in activities Changes in eating and sleeping habits

Restlessness and agitation Feelings of worthlessness and guilt Lack of enthusiasm and motivation Fatigue or lack of energy Difficulty concentrating Thoughts of death or suicide

Some of these may be symptoms of other conditions such as anxiety, ADD/ADHD, lack of sleep.

Check out this link for more information: http://www.helpguide.org/mental/depression_teen.htm