Have you ever found yourself preoccupied constantly with a person whom you do not have in your life anymore? This can be an old friend, love interest, trainer, teacher, or simply a person you once met, yet for some reason can't get out of your head. Psychology suggests that there are many reasons why some individuals leave such a strong impact on us.One of them has to do with emotions. Humans tend to remember everything that they have some kind of emotional connection to; this emotion might include being happy, passionate, loving, grieving, or even sad. If a person had something to do with events of your life where you experienced these strong emotions, it makes it more likely for you to remember them because of those EmotionsThe second explanation is associated with "unfinished business." This notion refers to situations when people do not receive any closure on their experiences, leaving them without answers or solutions. Consequently, the brain tends to replay such moments and look for a solution, which means that these memories take up a lot of mental resources compared to the completed experiences.Attachment styles also prove significant. Based on what one experiences in life, one will develop different attachment styles towards others. When there are people who give one a sense of security, importance, or strong connections, one tends to hold on to them. On the other hand, unpredictable relationships can be mentally consuming since the brain continues to process what went on during interactions with those persons in search for understanding.Then, nostalgia is also another element to consider. In some instances, missing someone could mean having fond memories of how one was while that particular individual was around. Perhaps they remind someone of a time when he/she was happier, more positive, or learning something new. In such situations, memories will be attached to something bigger than oneself.Generally speaking, the individuals who stay inside one's head are so special because they made some changes to him/her and left an everlasting impression. There could be someone who had a profound effect on one's thoughts and emotions, or he/she taught one a lesson that one would never forget in life.Dr.Samant Darshi, Consultant- Pschytarist , Neuromodulation expert & De- Addiction Specialist, Psymate Healthcare , Noida.