The Oxford Dictionaries define enisle as:
Isolate on or as if on an island. It supplies this example:
"in the sea of life enisled, we mortal millions live alone"
In the context of the question at hand, the subject is purposefully isolating him/herself from social contact for private time. The beauty of enisle is the word picture it paints of isolation as if on an island, although this isolation can be surrounded by activity. Albeit, this word is very seldom used in casual conversation.
In the context, here is my example:
"I enisle myself from colleagues, to buy time for reflection."
"Social sequestration is my gateway to contemplation."
Note: Others had already offered this before I made my initial post, so I will defer to them. However, sequester is most often used in the legal sense of separating jurors from outside contact. Hence, the connotation is of an outside authority imposing the separation.
p.s. Please excuse my earlier terse response. I'm still learning proper list etiquette.