You should try it sometime. I find that somewhere between 5 1/2 and 6 hours of sleep keeps me at peak performance, but 8 or 9 hours of sleep leaves my groggy and tired throughout the day. Paradoxical? Maybe, but our bodies are complicated machines.
This happens to me to, although it changes depending on the season. In winter I need more sleep and I'm just less productive. In the summer 5 hours of sleep and breakfast can keep me going all day.