Do Long Work Hours Affect Code Quality?

tooTired asks: "At my company the owner is heavily implying that the development staff needs to start working longer hours and weekends to shorten the time-frames on our current projects. The exact quote is 'These 8 hour days have to stop, we need to be working 15 hours a day and weekends, balls to the wall.' We are heavily under-staffed even with my multiple attempts to show the owner that we need more resources. My general feeling is that long hours is generally a symptom of poor project management, and not something to be sought after. I wanted to ask the Slashdot community their opinions on how working long hours during the week and weekends affects the quality of the code they produce, and the overall success of the project." A large reason why many in this industry find themselves working long hours and weekends is that management makes unreasonable expectations and deadlines. Are there ways of communicating to management that long hours to rush a project to completion is not the way to complete a successful project? Update: 08/30 23:11 GMT by C :Grammatical errors in title, corrected. Sorry about that.