Studies confirm and brain scans show that for someone with an Internet addiction, being online activates the brain's reward center just like an abused drug does.

If you think someone you know may be suffering from Internet addiction, look for the following signs:

• Preferring being online to spending offline time with others

• Feeling empty without Internet access

• Losing sleep because you're online instead

• Getting defensive if others say you spend too much time online.

The results of addiction? Just like drug addictions, Internet addiction diminishes  physical activity, causes a lack of face-to-face time with family and friends (and the world in general), and contributes to everything from obesity and lower self-esteem to problems at work, school and with friends.

How to get unhooked? One study found that when problematic Internet users had Internet access cut off, their withdrawal symptoms included increased anxiety, depression, heart rate and blood pressure.

That's why to disconnect you may need:

• A healthy habit substitute: The best is regularly-scheduled physical activity

• A family Internet schedule and whole-house Internet vacations so you spend time together talking, adventuring, or cooking

• Help in the form of cognitive behavioral therapy