Passage Summary: The theory is that if you count sheep, you are using both sides of your brain so much that there is no room left for the annoying thoughts that keep you awake.

Conclusion: Counting sheep is an effective way to fall asleep because it occupies both halves of the brain, thereby blocking out thoughts that keep a person awake.

Reasoning: The left brain is busy counting and the right brain is busy imagining the sheep; since sleep-preventing thoughts can occur in either half, this total occupation prevents those thoughts from surfacing.

Analysis: This argument relies on a significant 'Gap' regarding the brain's capacity. It assumes that if the brain is busy with one task (counting or imagining), it cannot simultaneously process another task (the sleep-preventing thoughts). To identify the necessary assumption, ask yourself what must be true for this 'exclusion' to actually happen. If the brain could multitask and handle both the sheep and the worries at the same time, the conclusion would fall apart. Look for an answer that confirms the brain's inability to process these two types of thoughts concurrently.