It's normal, on occasions, to go back and double check that the lights are switched off, worry that you may have not washed your hands clean or have events like these which are unpleasant but normal. People who have Obsessive Compulsory Disorder (OCD), obsessive thoughts become so consuming that they interfere in a person's daily life causing anxiety, uncontrollable, unwanted thoughts and repetitive behavior which make the person perform particular tasks without hesitation and with a frequency higher than most people. These obsessions are involuntary and may involve thoughts, images or impulses that occur over and over again in a person's mind, being a cause of disturbance and distraction to the patient.
OCD usually begins in the teens or young adult years but it can start later in life as well or very early on depending on the person's upbringing and lifestyle Symptoms of OCD usually begin gradually and tend to get worse throughout life or during stress conditions or anxiety attacks.
Observing people with OCD has given scientists some idea, however it still remains one of most intriguing behavioral patterns for scientists and doctors. Data indicates that it is a genetically inherited and cause chemical, structural, and functional abnormalities in the brain. Many studies have also showed that early life depression, anxiety, stress, trauma are also leading causes.
OCD's have various themes and usually fall in one of the following categories
1) Washers are afraid of contamination. They usually have cleaning or washing hand compulsions
2) Checkers repeatedly check things they usually associate with harm or danger.
3) Doubters and Sinners are afraid that if everything isn't perfect or done the way they want terrible things will happen.
4) Counters and Arrangers obsessed with symmetry and order. They have superstitions about certain numbers or colors.
5) Hoarders compulsively hoard things that they don't need or use and hesitate to throw things away
Just because you have obsessive thoughts or perform compulsive behaviors sometimes does not mean that you have OCD. It is normal human tendency to have repeated behaviors and obsessive thoughts, however it is only classified as OCD if the person after being repeatedly shown his behavioral problems still persists with his actions.