Text of a Dead Sea Scroll thanksgiving hymn references "darkness" as expression of sadness.
Thanksgiving Hymns, (1QH), in Florentino García Martínez and Eibert J.C. Tigchelaar, eds., The Dead Sea Scrolls Study Edition (Leiden: Brill, 1997) (Hebrew: 172, 174) (English: 173, 175)
The light of my face has become gloomy with deep darkness, my countenance has changed into gloom. . . For my eyes are blinded by the grief and my soul by the bitterness of the day. Agony and pain surround me, shame covers my face, my bread has turned into quarrel and my drink into argument