How does isolating himself emotionally help Beah to survive his experiences in the Sierra Leone civil war?

Beah's experiences force him to deny his emotional side in order to survive. His flight from RUF attacks on the various villages in Sierra Leone requires him to let go of attachments to family and friends. Although he holds out hope to see his family, he has no choice but to close off himself to the world. Emotional attachment can be weakness, and weakness can get you killed. Even when he joins forces with groups of friends (first Talloi, Gibrilla, Kaloko, and Khalilou, and later, Kanei, Musa, Saidu, Jumah, and Moriba) Beah remains emotionally distant from his companions. When the boys bury Saidu, they know that they will never visit to his gravesite, despite the villager's efforts to comfort them with an open invitation to return. Over the months on the run, Beah gets separated - sometimes in death - from his companions. The unpredictability of his life dictates that he stay detached. Even after he has begun rehabilitation, he is only able to call Esther a "temporary" friend. He has been living too long with the goal only to remain alive for one more day.

When he becomes a soldier, Beah's trainers use drugs and emotional manipulation - teaching the boys to picture their targets as the men who burned their villages and killed their families - to push the boys to acts of violence agains the rebels. Beah finds that he must suppress his emotional reaction to the atrocities he commits or lose his focus and, thereby, his life.