Again the night was too short. The lack of sleep is noticeable, among other things, in burning, dry eyes. Because: Too little sleep messes up the composition of the tear film. The altered mix of molecules in turn stimulates the corneal cells to divide more. This is reported by the team led by Wei Li from Xiamen University in Fujian, China, in the specialist journal »Stem Cell Reports«.
The researchers examined the cornea and tear fluid of mice that had been sleeping too little for either a few days or one to two months. This showed that potentially damaging oxygen compounds in the tear fluid increased during short-term sleep deprivation. At the same time, the concentration of antioxidants that protect the cornea from aggressive oxygen compounds decreased. The harmful molecules in turn stimulated the progenitor cells of the corneal tissue to multiply. After the mice were treated with the antioxidant L-glutathione, the cells began dividing less frequently again. If the rodents got less sleep in the long term, the corneal layer in their eyes thinned out – a possible sign that the corneal stem cells had been damaged and fewer new cells were being formed.
The transparent cornea breaks the incoming light and is therefore important for sharp vision. It is covered by a protective tear film. When irritated, the eyes burn and itch. Severe corneal injuries also impair vision.