Upon turning on my laptop, and off, my computer screen turns black for about a second then reappears?

I don't know if this is, or isn't normal, but I bought a Sony VAIO laptop about a week ago (Windows 7, Core i5, 4G Ram, 64 Bit) and it works beautifully. However, when I turn on my laptop, and the little windows jingle plays, the computer screen stay black for about 4-5 second before anything else appearing. Also, when I turn off the computer, the screen turns black for about 2 seconds then reappears and turns off. Is this a normal thing for laptops to do?