Even if Owls work the same number of hours as larks, they are perceived to be lazier. That is the conclusion of this article:
The belief that getting an early start to the day is virtuous is widely held. In fact, finds a forthcoming study, it’s so pervasive that managers rate workers who get an early start higher than those who get in and stay late, no matter how many hours they work in total or how well they do their jobs. And it could explain why other research has found that workers who have flexible schedules have less successful careers.
The study, from researchers at The University of Washington, highlighted at the Harvard Business Review, will be published later this year in the Journal of Applied Psychology. It finds support for the idea that managers have a “morning bias.” In other words, they buy into a common stereotype that leads them to confuse starting time with conscientiousness. They perceive employees who start later as less conscientious, and consequently less hard-working and disciplined, and that carries through to performance ratings.