The scoop on REM and what your eyes do while you’re sleeping
You’ve probably heard the term “REM sleep” or “REM cycle” in the context of sleep, but has it ever occurred to you that the “E” stands for “eye”? That’s right – Rapid Eye Movement (REM), hence our interest in the topic. Even though your eyes aren’t helping you “see” while you’re sleeping, they are still serving a very important purpose.
REM sleep is a relatively new term created roughly 60 years ago to describe the stage of sleep during which our eyes dart around rapidly. There are four stages of sleep, and REM is the last. The first three are described as non-REM sleep (NREM).
Stage 1 NREM – During this (approximately) 10-minute stage (5% of total night’s sleep), your heart rate and breathing slow down, and your blood pressure and brain temperature decreases. This is the in-between or “twilight” stage.
Stage 2 NREM – Adults spend most of their sleeping time in this stage (45% – 50%), which takes about 20 minutes to pass through. You are in a light sleep at this point, and your heart rate, blood pressure, and overall temperature continue to decrease to prepare for deep sleep.
Stage 3 NREM – This stage is considered “deep sleep.” It’s when your body repairs itself, grows, and builds up your immune system. This stage kicks in about 30 – 40 minutes after you fall asleep and constitutes about 35% – 40% of your total night’s sleep.
Stage 4 is REM sleep (20% – 25% of your total night’s sleep), which happens about an hour and a half after you fall asleep. Your first round of REM sleep in a night will last about 10 minutes and the subsequent rounds will increase and can last up to an hour during early morning rounds.
REM and Your Brain
During REM sleep, your brain shows the largest amount of activity, resulting in increased heart rate, quickened breathing, eye movement, and dreaming. Your primary visual cortex—the part of your brain that receives visual stimulus first when you are awake—is highly engaged in this stage of sleep. While the reason behind such active eye movement in this stage hasn’t been officially confirmed, studies suggest our eyes are moving in response to images in our dreams.
Dreams can also take the form of our brain processing things we’ve learned during our waking hours. The neural connections that result help build up our memory. This helps explain why a lack of sleep has such negative effects on our minds, e.g., trouble focusing, forgetfulness, stress caused by confusion.
REM and Your Motor Skills
During a normal REM cycle, your arms and legs are, in effect, paralyzed. This is beneficial because it keeps you from physically responding to your dreams. In a condition called REM Behavior Disorder, the part of your brain that shuts down your mobility malfunctions. People have been known to strangle their spouses, run into furniture, and injure themselves as their body tries to act out or respond to threats in their dreams. Thankfully, there is medication that can help control this condition.
REM and Your Eyes
In addition to mental effects, lack of sleep can also be a detriment to your vision. Many of us have experienced dry eyes after pulling an all-nighter or blurry vision after losing sleep over a report or sick child. Over time, the effects can actually cause serious damage to your eyes in the form of ischemic optic neuropathy (a lesion on your optical nerve) or swelling of the optic nerve, which can lead to vision loss.
It’s hard to believe that your eyes and sleeping habits are so intertwined, but it’s true! Whether it’s in the form of REM sleep causing your eyes to dart back and forth, or just general rejuvenation of your eyes in the other stages of sleep, it’s clear that getting a good night’s sleep is beneficial for your mental and physical health—including your eyes!
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