Lose One's Head Meaning

Example : 1884, Henry James, The Author of Beltraffio, ch. 4:  Mrs. Ambient's grief was frantic; she lost her head and said strange things.1914, D. H. Lawrence, "A Sick Collier" in The Prussian Officer and Other Stories:  Losing his head entirely, the young collier raved like a madman, what with pain and fear of hospital.2003, Bill Keller, "Walter Sisulu, Mandela Mentor and Comrade, Dies at 90," New York Times, 6 May (retrieved 12 Dec. 2009):  "He never lost his head in a crisis," Mr. Mandela wrote of his comrade.