Sleeping is one of the most important functions we perform all throughout our lives. In fact, we spend about a third of our lifespan just sleeping. It is a state of recovery and restoration and of solidifying and cataloguing information we have retained throughout the day.
While a great number of people assume that the body simply shuts down until it is time to wake, in reality, your body remains quite active throughout the night.
In particular, many people seem to think that when you shut your eyes, they cease to function until you open them again. This is simply not the case.
But what do your eyes do in this time? Do your eyes roll back in your sleep, or do they simply remain still?
Eyes During REM Sleep
On average, a person cyclically undergoes five stages of sleep throughout the night.
- Stage 1 is a light sleep more akin to a doze, where you drift in and out of sleep and can be awakened very easily. Your eyes will begin to move slowly underneath your eyelids and your muscle activity will also begin to slow. Many people seem to experience a feeling similar to sudden muscle contractions before they reach a sensation of falling in this stage.
- In Stage 2, your eye movement will stop and your brainwaves will slow in preparation for deep sleep. Your body temperature and heart rate will begin to drop during this stage as well.
- Stage 3 is the first stage of deep sleep, where extremely slow brain waves (known as delta waves) are interspersed with smaller, faster waves. People who have tendencies to sleepwalk, have night terrors, talk during their sleep, or wet the bed will most likely do so in this stage of sleep. There is no eye movement or muscle activity in this stage.
- Stage 4 is the deepest portion of sleep when the brain will produce delta waves almost exclusively. Typically, the deep sleep stages provide the most restoration. When roused from this state of sleep, people will often feel very disoriented for a few minutes upon waking. There is no eye movement or muscle activity in this stage either.
- REM sleep, or rapid-eye-movement sleep, is the last stage of sleep you will reach before eventually looping back to the first stage again. This stage of sleep is when you are more susceptible to having vivid dreams, due to the intense amount of brain activity that occurs. In fact, the amount of brain activity in this state almost mirrors that of a person who is awake. As a result, it’s labeled REM sleep because your eyes will move rapidly back and forth as you dream.
This eye movement during sleep can reach angular speeds of up to nine hundred degrees per second and is also known as a saccade.
It is not entirely clear why our eyes move so much during this stage of sleep. Some studies have proven that the visual cortex, or the part of the brain that processes images, is very active in this state, leading scientists to theorize that sleeping people are perhaps following the images of their dreams.
Your closed eyes are certainly not sending any visual information to your brain here, however. This process may also simply be a mark of a memory-forming or memory-reinforcing process that helps you lock in the memories of what happened the previous day.
A person may go through this stage in their sleep cycle anywhere between four to six times a night.
It takes about thirty seconds for your brain to recognize that it is time to wake. This may be why you do not see complete images right away after waking up.
Your Eyes and Light
Even when they are closed, your eyes are able to sense light and darkness, which is why bright lights or sunlight often wake people up. Light can increase a person’s alertness, which in turn may interfere with their sleep patterns or cycles.
In fact, looking at your phone screen, laptop screen, or any other type of electronic screen right before you sleep may be detrimental. This is because these devices emit blue light, which is a backlighting these devices use to mimic the brightness of the sun.
While this is not much of a problem during the day, constant exposure to artificial blue light at night may disrupt your circadian rhythm, resulting in sleep disorders and an increased risk for other health concerns such as depression or even cancer.
You may not even be able to reach REM sleep or the deeper sleep stages if you continue to expose yourself to this artificial blue light.
Rather than risk this harmful overthrow of your circadian rhythm, it is best to let your eyes rest and adjust to the lack of light naturally before resting.
What are your thoughts on eye movement during sleep?