expression, adverb
for amusement; to distract oneself from grief
Used when someone does something to relieve pent-up frustration, sadness, or stress. Often follows verbs like 行く, 出かける, 飲む.
憂さを晴らしにカラオケに行った。
I went to karaoke to blow off some steam.
彼は憂さを晴らしに酒を飲んだ。
He drank to drown his sorrows.
気晴らし is a noun meaning 'diversion' or 'pastime', while 憂さを晴らしに is an adverbial phrase specifically about relieving emotional distress.
From 憂さ (grief, sorrow) + を + 晴らし (continuative form of 晴らす, to dispel) + に (adverbial particle). Literally 'in order to dispel one's gloom'.