You're just tired and probably not eating exactly right. Also, getting enough water every day isn't easy. Most people do forget stuff like keys ALL the time. So, ever since I have lived away from family, I put my keys in the same place. When I used to carry a camera, tht's where it went, too. But now, socks and pens, hon, one time I thought there must be a planet called "Lost," where all the socks and pens went.