I wake up early, around 5 am, everyday. If I went to bed late that only means that my focus and concentration suffers the next day – I feel as a zombie all day, and have trouble putting sentences together. Cats jumping and playing around all nite long, only makes it worst. The foggy feeling continues all day – and despite all the coffee – unless I imitate my feline friends and take a quick catnap. It may be 15-20 minutes but it certainly makes a difference – I feel refreshed and my mind is a bit more clear. It also helps me with energy levels.
For some, it may be difficult to take a quick 15 minute break of shut-eye, but resting your eyes by closing them and maybe closing the door to your office (or going to the restroom) may work, if you need that jolt of energy. Even after you get home, you can benefit of those fifteen minutes if you need them.
For writers, especially if you have a crazy schedule and are balancing many projects at once, catnapping will work wonders. It gives you that little extra jolt of energy to focus much better.
At one point, taking naps used to be a common thing in our society; we became busier and hurried, relinquishing this short pleasure. Some cultures still use naps, and I bet you they live in a less cranky society. The amount of daily noise in our lives has also intensify, making napping almost impossible. If you live in a large city, then that might not be a problem, since you are used to sleep thru all kinds of noises.
My point to all this rambling is to use cat naps as a tool to help your focus and writing disposition, especially when you have deadlines, and may have gone to bed late at night. A catnap on time may save a squiggly line.