Too little, too much, or just right.

Everyone can feel the effects of a bad night’s sleep, and how long you let your head hit the pillow plays an important role in how your brain ages.

Scientists have now found that the amount of sleep you get each night doesn’t just result in brain fog and under-eye circles, but speeds up your biological aging as well.

Unlike chronological age — the number of years you’ve been alive — biological age is how much wear and tear your cells and tissues have experienced over a lifetime.

And biological aging is affected by several factors, including genetics, stress, diet, environment and sleep.

In a study published in Nature, researchers found that 6.4 to 7.8 hours of sleep each night was the sweet spot for healthy aging throughout the body.

The team examined 23 biological “aging clocks” from 500,000 participants aged 37 to 84 who self-reported how much sleep they got each night.

Data from each clock was analyzed to determine whether various organs, including the brain, lungs, liver, immune system, skin, heart, pancreas, fat tissue and more, were functioning older or younger than the participant’s calendar age.

A pattern that appeared in nine of the clocks showed that sleeping less than six hours and more than eight was linked to faster biological aging, higher disease risk and a greater chance of dying earlier.

However, the exact range of the perfect amount of sleep necessary for better aging changed depending on the organ being measured and gender.

But both short amounts of sleep and sleeping in longer affected the body, just in different ways.

Short periods of sleep resulted in wide-sweeping physical and mental health risks.

This included links to cardiovascular disease, high blood pressure, type 2 diabetes, obesity, kidney disease, low back pain, osteoarthritis, depression, anxiety and substance use disorders.

Meanwhile, getting more than eight hours of rest a night had different results.

Sleeping too long more often affected the brain, and showed up as conditions like major depressive disorder, schizophrenia, bipolar disorder and ADHD.

These could indicate an underlying condition already happening in the brain or body, rather than a direct risk factor.

Both sleep patterns carried a higher risk of death from any cause, though, as short sleepers had a 50% higher risk, while long sleepers had a 40% chance.

While the self-reported sleep duration offers different results than measurements from a clinical study, the researchers believe that these findings show how much the body keeps score when it comes to rest, and not just in the brain.