Does closing blinds affect temperature control?

I stay in an upper floor bedroom, but the windows face a cliff side so I rarely get direct sunlight during the day (usually in the morning). I was wondering if closing my blinds while I'm using my AC will help with temperature control. Basically I want to use an AC unit I have to get the room down to a nice temperature, turn it off and turn it back on again when it gets too hot, and I want to maintain the coolness for as long as possible.