Why do people have red eyes?

Red eyes can have a variety of causes. Some of the most common include:

- Eye irritation: This can be caused by a variety of things, such as allergies, dust, smoke, or chemicals.

- Lack of sleep: When you don't get enough sleep, your blood vessels can become dilated and your eyes can appear red.

- Crying: Tears contain a substance called lysozyme, which can irritate the eyes and cause them to appear red.

- Alcohol consumption: Alcohol can cause your blood vessels to dilate and your eyes to appear red.

- Smoking: Smoking can irritate your eyes and cause them to appear red.

- Medical conditions: Certain medical conditions, such as conjunctivitis (pink eye) and uveitis, can cause eye redness.

If you have persistent eye redness, it is important to see an eye doctor to determine the cause and receive treatment.