Merriam-Webster lists middle age from 45 to 64, while prominent psychologist Erik Erikson saw it starting a little earlier and defines middle adulthood as between 40 and 65.
《梅里亚姆-韦伯斯特》將中年定義在45歲到64歲 ，而著名的心理學家爱利克·埃里克森認為中年開始的時間較早，將中年定義在40歲到65歲。