Your redness of the eyes may be caused by the dryness of the eyes although you don't feel any hurt. However it may cause other eye problems which you need to pay attention to. You may have the cold in the eyes because of the long time use of eyes in front of the computers. You should have the good rest and use the eye drops to release the redness of the eyes.
Yes, it's possible that you could have simple viral pink, which is a condition that your eye is red but doesn't hurt. It can also be the reason of your blood vessel from your rubbing your eyes for example. You need to go to a doctor if your condition goes on and you may try eye drops to get rid of it. You can still change your pillow case too.
Relax and don't worry about it. It is very common to have red eyes without pain feeling. There are many vital and delicate blood vessles in eyes,which can supply blood to the cells. They are very small and easy to get irritated and dilated, which gives the eyes redness appearance. Some simply daily actions would cause the redness of eyes without pain, for example crying, coughing, sneezing, laughing or vomitting. Because the capillaries in eyes are very delicate and vulnerable, some easy actions with force would break or irritate or dilate them and the redness is resulted. Don't worry it happens all the time. I always find my eyes full of bloodshots and watering after I vomitted. The redness woudl clear out in a few minutes with no requirement of any treatment.
When you are tired or lack of sleep, your eyes will turn red without any hurt or pain. For this reason, you need to have a rest and enough sleep. The most common cause red bloodshot eyes in people who don't where contact lenses are eye allergies, known as allergic conjunctivitis. Although the eyes often itch, they may not. There is sometimes accompanying nasal allergies, characterized by sneezing or nasal congestion. The causes of eye allergies are numerous, but common ones include mold, mites, and pollen. Your doctor will be able to prescribe eye drops or other allergy medications for you if this turns out to be the diagnosis. Mechanical irritation of the eyes from small particles in the air (dirt, dust, smoke) is also common in some occupations and also in runners and others who spend a lot of time outside. This usually responds to wearing protective eyewear and using rewetting drops or artificial tears.