According to your description, it is maybe because that you didn't sleep well at night or sleep too late and did not get enough rest. When people stay up late lat night, or overuse their eyes too much leading to eye fatigue or eye dehydration, their eyes will become owing to the congestion of the blood vessels around the eyes. As well, if you do not sleep well at night, for example, you dream too much or so, you will have your eyes get congestion. To prevent your eyes from becoming red in the morning, you should not read or work for too long time without adequate rest. Remember to take a break when you have worked or read for an hour and do some eye exercises. Besides, if possible, do not stay up too late at night, and go to bed at a regular time. before sleeping, drink a glass of milk to help you be asleep easily and sleep well. Do not watch too exciting TV activities or movies or horror stories before bedtime which may cause unstead sleeping and nightmare that affect the quality of your sleep.