In case of an accident the explosion and related fires are going to pretty much destroy anyone's night visioin, passenger or flight attendant. If there is no explosion or fires and electrical power is still available, the lights would come up for emergency exits. If no electrical power is available, the flight attendants have plenty of high power flashlights readily available.

The real answer has already been given. When departing or landing a flight crew switches the plane's electrical source from the engines (turning generators) to an auxilliary power unit (usually located in the tail). The reason being is that if an engine fails during the most critical phases of flight you do not want the remaining engines to be burdened with generating (mostly) extraneous electricity. However, the APU is much smaller than the combined electrical output of the engines, so electrical demands are reduced somewhat. In smaller planes the pilots do not want the glare to affect their forward vision (obviously not a problem in a closed and locked cockpit.) There are probably other reasons (dim lights tend to subdue the passengers somewhat, I have noticed) but mostly it is due to the reduced electrical capacity during the critical phases of flight.

Having you close your window screen is a new one for me. Sounds like a cranky flight attendant, or maybe the sun was shining is someone's face. (kind of tricky at night, though)

Freightdawg