The short answer

We rub our eyes when we're tired in order to moisturize dry eyes and to stimulate our vagus nerve which helps prepare us for sleep.

The long answer

The urge to rub your eyes when you're tired is a universal human instinct – even babies do it! There are two main reasons you feel the urge to rub your eyes when you're tired:

Reason #1: Your eyes are dry.

As we get tired, our eyes tend to blink less often in order to keep us awake. This leads to dry eyes. Rubbing your eyes stimulates your lacrimal gland (responsible for tear production) which helps our eyes feel less dry.

Reason #2: Your body is preparing you for sleep.

When we rub our eyes, we are putting pressure on the eyeballs themselves. This act sends a signal to our vagus nerve which causes our heart rate to slow. Rubbing your eyes, in essence, is a way your body relaxes you and prepares you for sleep. For this reason, it's not uncommon for people to rub their eyes when they are stressed.

🧠 Bonus brain points

Why does it feel good to rub your eyes?

When you rub your eyes, you are stimulating tear production which makes your eyes feel less dry, and you are sending a signal to your vagus nerve which causes you to relax.

Is it bad to rub your eyes?

As a big fan of rubbing my eyes, I must regrettably report that, yes, it is bad. You shouldn’t rub your eyes because you can damage and weaken your cornea by rubbing your eyes. It also raises your risk of infection (hello pink eye), and it even increases the likelihood of dark circles under your eyes. Rubbing puts pressure on the skin around your eyes, potentially bursting small blood vessels which causes darkening.

Sources

Carniol, E. (2023, May 4). Why Do We Rub Our Eyes When We’re Tired and Why We Should Not. Carniol Plastic Surgery. https://drcarniol.com/rubbing-eyes/

Cleveland Clinic. (2019, July 19). 3 Reasons Why You Shouldn’t Rub Your Eyes. Cleveland Clinic. https://health.clevelandclinic.org/3-reasons-why-you-shouldnt-rub-your-eyes/

Essilor of America. (n.d.). Why Does Rubbing Tired Eyes Feel Good?. Essilor Eyeglass Lenses. https://www.essilorusa.com/newsroom/why-does-rubbing-tired-eyes-feel-good

Vu, L. (2022, May 24). Top Reasons Why You Shouldn’t Rub Your Eyes. Linda Vision. https://www.lindavision.com/2022/05/24/top-reasons-why-you-shouldnt-rub-your-eyes/