Social withdrawal is categorized into three types:

1. Shyness caused by fear or anxiety
2. Avoidance, caused by a dislike of socializing
3. Unsociability, caused by a preference for being alone.

• Since ancient times, people know the connection between isolation and mental focus. Cultures with traditions of old religions believe that solitude is important for enlightenment.
  
• A loner's brain goes in a state of active mental rest, due to the stillness of being alone. When we are with people, the brain can’t help but pay attention. That can be termed as a distraction.
  
• Daydreaming in the absence of such distractions activates the brain’s default-mode network. This network helps to consolidate memory and understand others’ emotions. Letting a mind wander helps with focus in the long term and strengthens your sense of both yourself and others. 
• Periods of solitude actually help when it comes time to socialize, with the occasional absence of focus helping concentration in the long run.
  

There is a difference between useful solitude and extreme isolation. If someone stops caring about people and cuts off all contact, this could point to pathological neglect of social relations, becoming dysfunctional - this is dangerous.

Being a creative loner while having interactions, is about striking the right balance, and any form of extreme behaviour is unhealthy.

• It’s hard to be introspective, self-aware, and fully relaxed unless you have occasional solitude. 
• Introverts tend to have fewer but stronger friendships – which has been linked to greater happiness.