You only smoke a few cigarettes a day, so you're not really hooked, right? Wrong.

"Smoking restrictions mean people are lighting fewer cigarettes but inhaling harder," says Dr. Karl Fagerstrom, author of a study paper on the subject.

His research results suggest that a better indicator of addiction is the time until your first fag in the morning; less than 30 minutes means you're "heavily dependent."

Also read: Looking forward to quit smoking?