Green’s Dictionary of Slang

vtr. to cheer someone up, to improve someone’s spirits, vi. to cheer up, become happier.

1658		J. Ussher Annals of the World VI 542: Thus Asia, which before was plagued with the Publicans, and opressed by the coverteosnesse and abuses of the garrisoned soldiers, begins to pirck up again.
1670		O. Heywood Diaries (1881) II 346: To bow down his head as a bulrush, which in a wet day stoops, but in a sun-shine day perks up again.
1706		E. Phillips New World of Words (6th edn) n.p.: To Perk up, or Perk up again, [...] to recover after Sickness.
1892		Gentlewoman’s Bk Sports I 163: You will soon perk up, quite ready to start again [OED].
1902		Ade Forty Modern Fables 297: He might as well Perk up and not overdo the Pining Away.
1915		J. Buchan Thirty-Nine Steps (1930) 116: After lunch, as I sat in the hotel porch, I perked up.
1928		M.C. Sharpe Chicago May (1929) 181: When the World War broke out most of us perked up. Hope was revived. If only the Germans would win!
1938		G. Greene Brighton Rock (1943) 104: This holiday’s perked me up.
1939		Wodehouse Uncle Fred in the Springtime 19: ‘Yes,’ said Horace, for the first time perking up and showing a little of the Pendlebury-Davenport fire.
1953		J. Thompson Savage Night (1991) 139: The rest and the stuff the doctor had given me seemed to have perked me up quite a bit.
1962		S. Longstreet Flesh Peddlers (1964) 137: I had perked up again.
1984		J. Ellroy Because the Night 20: Looking for something to perk his mental juices, he picked up the file that Dutch Peltz had given him.
1989		T. Blacker Fixx 168: They needed perking up too.
1997		L. Davies Candy 34: On about the sixth day we were beginning to perk up.
2005		B. Woodward Secret Man 19: I mentioned this graduate work [...] to Felt. He perked up immediately.
2017		R. Friedman Street Warrior 231: She perked up. ‘You can do that?’.
2022		G.M. Graff Watergate 199: Ehrlichman seemed to perk up when he heard the former attorney general was involved.