Dry eyes at night | Dry eyes

Dry eyes at night

The fact that many people complain about dry eyes, especially at night, has several causes. For one thing, the blink of an eye is missing when sleeping. As a result, the tear film can no longer be distributed so evenly over the cornea, nor are dirt, foreign bodies, cell debris, inflammation mediators and pathogens removed.

The interrupted flow of the tear fluid can then lead to the attachment of pathogens. In addition, the production of tear fluid by the lacrimal gland decreases at night during sleep. This favors not only the drying out of the eyes, but also the adhesion of pathogens, since the accessory lacrimal glands also stop the production of class A immunoglobulins (IgA).

IgA normally ensures a rapid defence against pathogens such as bacteria in the mucous membranes. As a result, fluid is absorbed through the conjunctiva at night instead of through tear gland production and eyelid blink as during the day. But even with dry eyes during the day, the eye can absorb fluid and oxygen via the vessels of the conjunctiva by means of a kind of ’emergency supply’.

Normally, oxygen is also absorbed through the air and the connection to the tear film, but this is more difficult in dry eyes. At night, this process becomes even more acute. As a result, especially people who already have dry eyes wake up with reddened, extremely dry eyes.

In addition, it can go so far that even the eyelids are swollen, since here too, vessels were used to supply the conjunctiva. When waking up or before going to bed, the use of tear substitutes can therefore be helpful.