Why do tired eyes become red and dry?

The night was really short. Lack of sleep is manifested by a burning sensation and dry eyes. After all, lack of sleep disrupts the formation of the tear film. The team, led by Wei Li of Xiamen University in Fujian, China, reported in the scientific journal that other molecules in it stimulate corneal cells to divide more. Stem Cell Reports†

The researchers analyzed the cornea and lacrimal fluid of mice that had not slept for a few days or one to two months. They discovered that short-term sleep deprivation increases potentially harmful oxygen compounds in the tear fluid. At the same time, the concentration of antioxidants that protect the cornea from aggressive oxygen compounds decreased. The harmful molecules, in turn, increased the number of precursor cells in the corneal tissue. After the mice were treated with the antioxidant L-glutathione, the cells divided again at a lower rate. In the long run, if the rodents get less sleep, the layer of the cornea in their eyes is thinned – the corneal stem cells may have been damaged and form fewer new cells.

The transparent cornea refracts incoming light and is therefore important for sharp vision. It is covered with a protective tear film. Eye irritation causes burning and itching. Severe injuries to the cornea impair vision.