Chinese idiom · 成语
昼思夜想
Meaning
Think of something day and night; feel deep, persistent longing.
Character by character
Origin and story
Literary expressionThe parallel phrases 'think by day' and 'think by night' express an attachment that occupies the mind continually. A documented literary use appears in Yao Kuan's Song-dynasty Xi Xi Cong Yu. In a discussion of Cao Zhi and the Rhapsody on the Luo Goddess, it quotes a commentary story describing Cao Zhi as longing for Lady Zhen day and night.
The romantic story includes a supernatural encounter and is not secure biographical evidence. Yao Kuan's surrounding discussion itself questions a transmitted account of the poem's origin. This is therefore evidence of the expression's use in literary tradition, not proof that the alleged romance happened or that it created the phrase. Modern usage simply describes deep, persistent longing.
Sources and further reading
In everyday life
在外地工作这些年，他昼思夜想的，始终是家乡那座小院。
Through these years of working away from home, it is the little courtyard in his hometown that he keeps thinking about day and night.
Expresses deep longing or continual preoccupation; 想 here means think of or miss, not necessarily dream while asleep.