Three a.m. is my favorite time to be fast asleep, corkscrewed into my coverlet. We had just put the air conditioner in the window, so we were ready to hold the temperature and humidity at bay if only for a few hours. The only problem is: We have to keep the bedroom door closed, and the cats are not used to being shut out. When I heard Cubby screeching at 3 o’clock, I figured I was dreaming. As I regained consciousness, I opened my eyes. Without my glasses, all I could see was a blurry grey figure on top of the armoire. Then it moved. Then it meowed. I glanced at the door, which should have been closed, and saw that it was wide open. Well, that solved one mystery. The mystery yet to be solved was who opened the door? I vote for Tommy, the 15-pound tuxedo cat who can easily stretch to the height of the door handle. I’ve never actually seen him open a door, but he can do lots of things when he sets his mind to it. He gets into the hall coat closet unseen and sometimes gets shut in. When he’s ready to get out, he yells and scratches until someone releases him. And he loves to get into the garage. I always check to see if he’s around before I open the door, but — bam — as soon as I turn the handle, he comes charging down the hall, bolts past me and heads directly for the farthest corner of the space. We have had no luck displacing him from his hidey hole between the boxes and the lawn equipment, so he stays there until he is ready to come out. Cubby likes heights, so I wasn’t the least surprised to find him on top of the armoire. As a little guy, hardly 10 pounds of gray and white cuteness, he seems to fly easily up to any perch which beckons. Lately, they have both discovered an empty bookshelf near the top of the built-in bookcase in the den. They literally climb the shelves and wedge themselves into the small opening, turning around so they have a view of the room. Coming down is another matter. Invariably, there are books or papers on the ledge below and also on the nearby stepstool. Tommy spends a lot of time planning his descent. Cubby just pushes off and lands as gracefully as an athlete at the Olympics. The recent nocturnal events did not end with my finding Cubby in the bedroom. I got up and got him out simply by leading him toward the kitchen and his food dish. Tommy materialized along the way and joined us. After a snack, I headed back to the spare bedroom, so at least my husband’s sleep would not be interrupted. Cubby was happy to hop into bed, and Tommy sat like a sentinel in the window. After a mere hour — long enough for me to fall asleep again — Cubby decided it was time to play. He sat on my pillow inches from my face and starting singing his morning song. He seems to think he’s a bird and chirps with them before dawn. I was not amused. I crawled out of the second bed and headed back to the kitchen. I sat down at the computer with a glass of milk while the guys did their morning calisthenics and chowed down on some tasty treats. Then I tiptoed into the den to try to grab 40 winks in my comfy recliner. They followed me to check out the perimeter and the view from the windows. Seeing everything was safe, they curled up on the floor and were asleep in a matter of moments. When my husband joined us a couple of hours later, he wondered why we were all in the den — and why one of us was so exhausted.