Separation anxiety disorder (or simply separation anxiety) is a psychological condition in which an individual has excessive and inappropriate levels of seperation anxiety which interferes with their ability to appropriately function and develop.
Being separated from their primary attachment figures, (usualy parents) or from the home environment naturally causes anxiety for children initially. It becomes a disorder when they do not adjust and remain fearful, inclined to social withdrawal, tantrums, school refusal etc in order to avoid the feelings.
Even though present in all age groups, adult separation anxiety is much less common than childhood separation anxiety and usually only manifests itself as a symptom of a bigger issue .
Separation anxiety is often characterized by some of the following symptoms:
Recurring distress when separated from the subject of attachment (such as the mother or home)
Persistent, excessive worrying about losing the subject of attachment - that some harm might come to them
Persistent, excessive worrying that some event will lead to separation from a major attachment
Excessive fear about being alone without subject of attachment
Persistent reluctance or refusal to go to sleep without being near a major attachment figure, like a mother