Why Are My Eyes So Dry and Tired by the End of the Day?

By Dr. Raj Dhadwal

It is late afternoon and your eyes feel like they have had enough. They sting a little, they feel gritty, as though there is grit under the lid that you cannot blink away. The screen has started to blur unless you concentrate. You reach for drops, they work for a few minutes, and then the tired, scratchy feeling comes back. It is worse in winter, worse in an air-conditioned office, and worse if you wear contact lenses. If that is the day you keep having, you are not imagining it, and it is worth understanding what is actually happening on the surface of your eye before you decide what to do about it.

This article is about the biology of that feeling and about what published research has examined. It is education about tear-film biology and food composition, not medical advice, and nothing here describes treating, curing or preventing any eye condition. If your symptoms are persistent or getting worse, see an eye-care clinician, because dry, tired eyes have many causes and some of them need proper assessment.

What is actually keeping your eyes comfortable?

The comfort of your eye does not come from tears in the way most people picture it. It comes from a structured coating called the tear film, and it is only a few micrometres thick. It has three parts working together, and each one matters.

The innermost part is a thin mucin layer, produced by cells on the eye surface, that lets watery tears spread evenly instead of beading up. The middle and thickest part is the aqueous layer, the watery fraction, which carries salts, proteins and oxygen across the surface. The outermost part is a very thin oily film, the lipid layer, produced by the meibomian glands that sit along the rim of your eyelids. Every time you blink, you spread a fresh coat of this three-part film across the eye.

The oily outer layer does an unglamorous but decisive job: it slows evaporation. Without it, the watery layer underneath evaporates far too quickly between blinks. So the health of that oily layer, and how well the meibomian glands produce it, is a large part of why some people feel comfortable all day and others feel dry by three in the afternoon.

Why do dry eyes actually sting and feel tired?

Here is the mechanism that ties it together. When the oily layer is thin or of poor quality, the watery layer evaporates faster than it should. As water leaves, the salts stay behind, so the remaining tear film becomes saltier, more concentrated. Scientists call this a rise in tear-film osmolarity, and a hyperosmolar, saltier tear film is one of the recognised triggers for the stinging, scratchy, tired sensation. The surface cells sit in a saltier bath than they are built for, and they signal discomfort.

Now add the modern day on top of that. When you stare at a screen, you blink far less often, and often only partially, so the film is not refreshed as regularly. Winter air and heating are dry, which speeds evaporation further. A contact lens sits in the tear film and can disrupt how it spreads. None of these creates a new disease on its own, but stacked together they are exactly the recipe for a tear film that thins and concentrates through the day. That is why the feeling arrives in the late afternoon rather than first thing in the morning.

What has the published research examined?

Because the oily layer is made of lipids, researchers have asked a reasonable question: does the fatty-acid supply in a person's diet show up in the tear film, and does that track with how comfortable the eye feels? Sea buckthorn, also spelled seabuckthorn, has appeared in this literature, because its oil is unusual in carrying omega-7 (palmitoleic acid) alongside omega 3 and omega 6 fatty acids. It is one of the things that has been studied for the tear film, and the honest way to read that work is as fact about the literature, not as a promise about your eyes.

Three trials are worth naming precisely, and so are their limits.

Study	Design	What it used	What it reported
Larmo and colleagues, Journal of Nutrition, 2010 (PMID 20554904)	Double-blind, randomized, placebo-controlled, about 100 participants randomized, with fewer completing	2 g of oral sea buckthorn oil daily for three months, in people with dry-eye symptoms	The usual seasonal rise in tear-film osmolarity was attenuated in the group taking the oil, and symptom scores were somewhat lower. Not every endpoint improved, and the authors themselves described the effect as modest.
Larmo and colleagues, Cornea, 2011 (PMID 21832964)	Randomized, from the same modest research programme	Oral sea buckthorn oil	Reported fatty-acid measurements in tear-film and blood samples from the same research programme. This was mechanistic composition work, not proof of eye-comfort benefit from a food.
Larmo and colleagues, Contact Lens and Anterior Eye, 2018 (PMID 30497904)	Randomized	A topical sea buckthorn eyelid spray, applied to the outside of the closed lids	Examined the spray's effect on tear-film and eyelid-margin measures. This was a small, topical study, a different route entirely from eating anything.

Read those rows carefully, because the caveats are the point. The oral trials used a concentrated sea buckthorn oil at a set daily dose, not a whole-berry puree, so the amount and the form are not the same thing as a food. The trials were modest in size and modest in the size of the effect they reported. The topical study tested a spray on the eyelids, which tells you nothing about eating a berry. And every one of these measured tear-film properties and symptom scores in study conditions; none of them makes sea buckthorn a remedy for dry-eye disease, and I am not presenting it as one. What the literature shows is that the fatty-acid supply from this oil was measurable in the tear film and that researchers found the topic worth studying. That is where the honest account stops.

What actually helps a tired tear film day to day?

The unglamorous measures are the ones with the least to argue about. Blink fully and deliberately when you have been on a screen, and give your eyes regular breaks from the screen so the film gets refreshed. Reduce the dryness of the air around you where you can. If you wear contact lenses, follow your clinician's guidance on wear time. And if the feeling is persistent, get the eyelid margins and the meibomian glands looked at, because a clinician can see things you cannot, and the cause dictates the fix.

Sea buckthorn is relevant to this article only as a food whose oil fraction has been studied separately in tear-film research. Those studies do not show that eating a whole-berry puree changes dry, tired eyes. If you want the wider picture of that fatty acid, we cover it in the forgotten fatty acid and in nutrition and the eye surface, and the eye-surface framing in omega-7 and eye-surface nutrition.

Where does this sit in a whole berry?

Human Renaissance is the only sea buckthorn puree in the world sold in a single-serve pouch. 190+ naturally occurring compounds, omega 3, 6, 7 and 9, 201 mg of vitamin C per pouch, 0 g sugar, 5,640 hand-picked berries per box.

Some of the same fatty-acid families discussed in the tear-film literature are naturally present in the whole berry, but the studies used specific oil preparations, not this puree. For the full composition see sea buckthorn nutrition facts. None of that is a reason to expect the pouch to change your eyes; it is simply what the whole berry contains.

The short version

Your eyes feel gritty and tired by the end of the day because the tear film, the few-micrometre coating that keeps the surface comfortable, has thinned and concentrated over the hours. Its outer oily layer, made by glands in your eyelids, is what slows evaporation, and screens, dry winter air and contact lenses all speed that evaporation up. As water leaves, the tears get saltier, and a saltier tear film is a recognised trigger for the stinging, tired feeling. Researchers have studied the dietary fatty-acid supply behind that oily layer, and sea buckthorn has appeared in three modest human trials that used a concentrated oil, not a puree, and reported effects the authors called modest. That is a fact about the research, not a promise about your eyes. The dependable day-to-day measures are fuller blinking, screen breaks, less dry air, and a clinician's assessment if the symptoms persist. This is education, not medical advice, and nothing here treats or cures any eye condition.