Several causes. Dry eyes are the leading cause of "bloodshot" eyes. Allergies, excessive hours spent at the computer, and contact lens over-wear are also major contributors. Another possibility is a pterygium or pingueculum, a growth on the white of the eye caused by sun exposure. There are several other possible causes, many of which can be easily treated. See an eye doctor for an evaluation and treatment.
Allergies/infection. You could have allergic conjunctivitis, or could be an infection. It could also be due to high blood pressure. You should go see a doctor to have it checked out.
Probably dry eyes. Generally this is worse in the morning immediately after you wake up. Includes red eyes and foggy vision early on that clears up. If this is the case, try some artificial tears during the day (3-4 times/day) and a ophthalmic lubricating ointment at bedtime. It might take about a week or so to notice a difference. Otherwise, get an eye exam for an evaluation. Good luck.
Dryness/allergy. If there is also itching, consider allergies other wise dryness/exposure is the most common reason.