Our eyes are constantly strained to look at things that are short distance. Examples are looking at the computer, the mobile phone and watching television.
This result in tired eyes.
One good remedy is to close the eyes to relax. Tired eyes can make our brain a bit dis-orientated and lose focus. This is why a pendulum is used in hypnosis (so that the eyes will become tired staring at it swinging left-right).
But please take caution to close your eyes only at appropriate time and place.