It’s likely you’ve experienced the phenomenon of feeling like you can’t possibly keep your tired eyes open for one second longer – possibly after a long day of living your best life or during every work-related meeting ever (kidding!). But why exactly does it happen?

Fatigue

Shocker, we know. Eyelids are made up of muscles. And much like our arms become tired after a long day of holding our phones to our faces, eye muscles become fatigued after all the blinking we do and require rest. Dr Kleinsasser, an eye specialist says, “During waking hours [our eyelids] are continuously blinking […] It’s analogous to being on your feet all day.”

Dryness

Having your eyes open for extended periods of time can lead to dry eyes. According to Dr Kleinsasser, the “heavy” feeling we experience in our eyelids is often a “protective mechanism” which forces people to shut their lids in order to lubricate the eye’s sensitive outer layer. Not doing so for long periods of time can cause irreparable damage to the cornea.

And that overwhelming need to rub your eyes when you’re tired? That also has a biological purpose. Rubbing your eyes can help do away with dryness by stimulating the glands in your eyes to produce more tear fluid.

Hormones

As if our hormones didn’t mess with enough things in our body as it is, according to Dr Parker, an ophthalmologist and corneal specialist, hormones can also play a role in causing our eyes to feel heavy. “Each day, as the morning progresses into the afternoon and then the evening, your body’s circulating adenosine, and melatonin levels rise, specifically to prepare the body for sleep,” he said. As a result, our body temperature, heart rate, and blood pressure drop. This is accompanied by a feeling of tiredness, which corresponds with a desire for the eyes to close.

There is truly only one thing that can help tired, heavy eyes, and that is sleep – not another cup of coffee.

Photos: Instagram and Unsplash