Well, I may get some flack for my opinion. The "experts" all say 12 hours or so based on the greys native nearness to the equator and the amount of daylight etc. However, for many of us, that would mean our poor birds would only have contact with us or be out of their cages a couple of hours a day. It's not like they are in the wild, flying miles and miles each day and foraging for food. Mine gets up with me about 5:30AM until he's back in his cage about 6:15. Then when I get home, he may be out of cage until 8PM, sometime even later. Therefore he gets about 9+/- of sleep time and doesn't pluck, scream, bite, etc. Just my opinion......jane