Many of my co-workers use laptops. When they disconnect them and take them home, the external Dell LCD displays (1907FP, 1908FP, 2007WFP, etc.) stay on, with a graphic indicating that there is no source connected to the monitors. The problem is, the displays never sleep, therefore wasting power (~40W for a 19" 5:4 panel). Over several people and many hours, this adds up.
My question: is there a way to get a Dell display to sleep when disconnected without powering it off? I'm looking for an automatic solution because it's a hassle to turn the monitor on and off every day.