After reading the following meta-poem, what is the reason why the poet's temples turn white?

This topic examines the ability to appreciate the content of poetry. Attention should be paid to analyzing the meanings of important words, such as "ten years" representing a long period of time; "Wan Fan" implies that someone or something that the poet has been paying attention to for a long time can never reappear; Zhu is a paper account. One night, the poet was dreaming in a warm paper account. The poet daydreams during the day and dreams at night, which makes his temple "flashy".