The habit of staying awake late into the night; the quality of being a night owl.
1958, Eli Greifer, How I Cured My Incurable Ailments, page 221:
To prevent the pressure from soaring once more to dangerous heights, I decided to increase the amount of sleep, despite the slumber-impairing heat of July, by yielding to a later night-owlism, i.e. to retiring at a time even a few hours after dawn, discounting the Daylight-Saving hour, and wearing but shorts.
1959, Weiss, The Executive, page 6:
As a people become more sophisticated, the tend toward night-owlism.
2012, John Francis King, Funky / Guy, page 13:
They were developing a flowing rhythm together: a healthy balance of night-owlism and early birding, although despite their proximity to the Heath they could probably have done with more fresh air.
