Final answer:
The best sentence encapsulating the main idea of the paragraphs about sleep disorders is that insomnia is not the only widespread sleep problem, suggesting the prevalence of multiple sleep ailments.
Step-by-step explanation:
When attempting to identify the main idea of the fourth and fifth paragraphs related to sleep disorders, it's crucial to focus on the comprehensive description provided. The paragraphs elaborate on a variety of sleep-related issues, including sleep apnea, narcolepsy, and the impact of sleep disturbances on daily life. Considering the provided text, option D that states 'Insomnia is not the only widespread sleep problem' best encapsulates the overarching theme by acknowledging that there are multiple significant sleep disorders affecting individuals.