During a vacation, or a trip to a familiar place, we may feel nostalgic thinking of loved or of earlier times spent with friends and family.

“For one thing, loneliness has been shown to be a trigger for heightened nostalgia. It is interesting because then the nostalgia helps someone feel connected again. It helps to decrease the negative feelings of being alone. When you are lonely, it is because you are separate from others in one way or another; and the holidays are really notorious for making people feel alone, even when they are not physically alone,” researchers said.
Source-Medindia