Most parents expect some emotional ups and downs as their child enters the teen years. If you are like most parents, you also probably know to keep an eye out for depression warning signs, such as drug and alcohol use, violent mood swings, and acting out. Not all symptoms of depression are as obvious, though. The following are little-known signs you should also keep an eye out for.

Sign #1: Concentration Problems

Does your teen seem easily distracted in a way that is out of character? If they are losing track of tasks that used to come easily to them, depression could be the root of the problem. Absent-mindedness, inability to stay focused on a single task, or lack of interest in things they were formerly interested in are all common indicators of an issue. Concentration issues alone don't necessarily mean your teen is depressed, but it is a sign that you should pay closer attention to make sure they aren't exhibiting any other signs.

Sign #2: Changes in Sleeping Habits

Teens need a lot of sleep – eight to 10 hours to be exact. This means a slight increase in their sleeping habits or a tendency to try and sleep in shouldn't immediately raise any warning bells. If increased sleep doesn't seem to be resulting in actual rest, though, it is time to get concerned. Teens that are sleeping or staying in bed for increased hours but still seem tired and listless may be battling depression. It can also work the opposite way – some teens may begin sleeping less and acting restless when they are depressed. Any major change in sleep habits is reason to investigate further.

Sign #3: Increased Negativity

Depression can cause a formerly upbeat or positive child to become increasingly pessimistic. They may stop doing activities they previously enjoyed, using excuses like they aren't really that good anyway. The teen may also refuse to try new things or put forth maximum effort because they already have the expectation of failure. Increased negativity can also present in less obvious ways, such as taking a "glass half empty" approach when discussing world events or even day-to-day happenings. Second guessing themselves is another sign of depression. The negative attitude can lead your teen to doubt their choices and abilities, making them seem suddenly more indecisive than usual.

If you are concerned about your teen, you may want to consider an outpatient counseling or psychiatric service. Getting your child treatment for their depression can save their life.