Sleep is an essential time for our bodies to recover, but what about our eyes? Although closed, they remain active in a specific way and play a key role in the regeneration and overall health of the eyes. Understanding what happens to our eyes during sleep can help us better understand the importance of good rest for preserving our vision in the long term.

Sleep Stages and Eye Activity

Sleep is divided into two main phases: slow-wave sleep (or non-REM) and rapid eye movement sleep (or REM, for "Rapid Eye Movement"). Each stage has a different impact on the activity of the eyes.

Slow Wave Sleep (Non-REM)

During this stage, which accounts for about 75% of our sleep, the eyes are closed and remain relatively still. Here's what happens:

• Reduced Eye Movements: During light and deep sleep, eye movements become slow, then almost completely stop. The muscles that control the eyes are at rest, allowing them to relax after a day of intense visual activity.
• Lubrication and Protection: With the eyelids closed, the eyes continue to lubricate themselves. The lacrimal glands produce tears to moisturize the ocular surface, which helps prevent dryness and protect the cornea. This also helps remove small particles of dust or accumulated impurities.

Remote Eye Movement (REM) Sleep

The REM (Rapid Eye Movement) phase is when the most vivid dreams occur. This is also where the Eyes show very specific activity:

• Rapid Eye Movements: During REM sleep, although the eyelids remain closed, the Eyes move rapidly in different directions. These rapid movements are often correlated with dream activity, as if the Eyes were "following" the scenes we imagine in our dreams.
• Brain Stimulation: During this phase, the brain is very active, and rapid eye movements are linked to intense neural activity. Scientists believe these movements are a response to images and events perceived during dreams.

Why Do Our Eyes Move During REM Sleep?

The exact origin of rapid eye movements during REM sleep is still debated, but several theories exist:

• Visual Dreams: One of the most common theories is that the Eyes move in response to the scenes and events unfolding in our dreams. This could reflect "internal visualization," where our Eyes react as if they were following objects or characters in an imaginary world.
• Neural Activation: Other researchers suggest that these movements are a consequence of the activation of certain areas of the brain related to vision. During REM sleep, the brain goes into "simulation" mode, and eye movements are thought to be a mechanical response to this activation.

The Role of Sleep in Eye Health

Sleep plays a crucial role in maintaining the health of the eyes, and here's why:

Repair and Regeneration

While we sleep, the body works to repair cells, including those in our eyes. Poor quality or insufficient sleep can affect the ability of the eyes to regenerate, which can lead to dry eyes, irritation, and even blurred vision in the long term.

Eye Condition Prevention

Studies have shown that insufficient sleep may be linked to eye problems such as dry eye syndrome or photophobia (increased sensitivity to light). Good sleep is therefore necessary to maintain fluid balance and prevent these discomforts.

Reducing Eye Stress

Our Eyes are exposed to a multitude of stresses during the day, whether from computer screens, phones, or constantly changing light. Sleep allows our eye muscles to rest, thus reducing fatigue and discomfort.

How to Improve Sleep to Better Protect Your Eyes?

Good sleep is essential for maintaining healthy eyes. Here are some tips to optimize the quality of your sleep and preserve your vision:

• Stick to a regular sleep schedule: Going to sleep and waking up at the same time every day allows your body and your eyes to better adapt to sleep cycles.
• Avoid screens before bed: The blue light from screens can disrupt the production of melatonin, the sleep hormone. Try to avoid screens at least 1 to 2 hours before bed.
• Hydrate your eyes: If you tend to suffer from dry eyes, moisturizing eye drops can be used before bed to promote moisture and protection.
• Create a sleep-friendly environment: A dark, quiet environment helps facilitate sleep and regeneration of the eyes. Also consider using blackout curtains to reduce distracting light sources.

Even while we sleep, our eyes continue to be active in subtle but essential ways. Whether during slow-wave sleep, when they rest, or during REM sleep, when they react to dreams, sleep is crucial for eye health. Taking care of the quality of your sleep is therefore a key element in maintaining healthy eyes and ensuring optimal vision, day and night.