'wide-awake' originates from English, a compound of Old English 'wīd' (meaning 'wide') and Old English 'awacan'/'awæcnan' (meaning 'to awake').

'wide-awake' developed as a compound phrase in Early Modern English (written as 'wide awake' or hyphenated) and came into established use as the adjective 'wide-awake' in later modern English.

Initially it described being thoroughly awake; over time the sense broadened to include 'alert' or 'watchful' in addition to simply 'not asleep'.