Stages of Sleep: Rapid Eye Movement & Non-Rapid Eye Movement

Editor's Note: This article has been recently updated with latest information and research studies.

So you think that if you just put your head on the pillow and drift off to sleep, that nothing else happens? It does seem that there is anything else involved by thinking like this way, but there are several stages of sleep that are repeated and reflected in our day time motivations and throughout the course of any given night that our sleep patterns will affect us.

Our brains are very active during sleep, and in this article we are going to explain each stage of the sleep process and what happens in our bodies.

We sleep in basically two stages: REM (rapid eye movement) and NREM (non-rapid eye movement).

Stages of Sleep

NREM sleep is compiled of mini stages (lasting approximately 15 minutes each), and then there is REM sleep which is achieved and the cycle is complete and then repeated.

“Now I lay me down to sleep”

Stage One of Sleep

The first stage of sleep is a very light sleep, and best known as a transition of time between wakefulness and sleep. At this stage, our brain waves are very slow and not much activity is going on. While in the first stage of sleep, you may be easily awoken and feel that you weren’t really asleep at all. This time period lasts about ten minutes. Perhaps you have experienced the feeling of “falling”, and have an involuntary jerk reaction of any of your limbs at this stage; this is referred to as “hypnic myoclonia”

Stage two of Sleep

The second stage of sleep could last up to twenty minutes, and it is at this time that the brain begins what is known as “sleep spindles“, which are bursts of rhythmical and rapid brain waves. Our heart rates begin to slow, and our body temperature begins to drop, in summary: our body is being prepared for a deeper sleep. During the night, we default into stage two of sleep.

Stage Three and Four of Sleep

Stage three and four are similar, with stage four being obviously deeper. If a person is awaken during stage three of the sleep cycle, they will be disoriented and confused about their surroundings for a moment or two. It might be more challenging to wake someone when they have reached stage four. These stages are, on average, about 15 minutes each, but it is possible to remain in stage four for 30 minutes. Stage three, in a healthy adult, takes up about 20% of the entire sleep cycle per night. Sleepwalking and bedwetting happens during the end of stage four of the sleep cycle.

Stages three and four, the deepest sleep of NREM is the crucial time that our bodies regenerates, restores and repair any tissues damage, builds muscles and bones and keep our immune system strong and healthy.

Rem Stage of Sleep

After stage four, we enter into a short period of REM (rapid eye movement) sleep. This is the stage of sleep when we dream and it usually takes about 90 minutes from the time you close your eyes to reach this stage. REM sleep progressively gets longer as the night goes on, starting for 10 minutes and ending at about 60 minutes by the time it reaches the last full sleep cycle. Infants spend 50% of their sleeping time in REM stage, whereas adults only spend 20% of the slumber in the REM stage of sleep.

Rapid Eye Movement is so named due to the fact that our eyes move rapidly (in all directions) under our eyelids. During the REM stage of sleep your heart rate quickens and your respiration may become erratic, for individuals that are not inflicted with any type of sleep disorder. It has been shown, through extensive studies, that the brainwave patterns during REM sleep are similar to the brain activity of someone fully awake.

Due to this active brain activity, vivid dreaming occurs. The interesting thing about REM is that even though the brain waves are very active and heightened, there is a paralysis of the muscular system. Some theories of this may be a protective measure that the body evokes to protect us from hurting ourselves during dreams. This is referred to as “paradoxical sleep“.

When researchers examine REM sleep, they have found that this stage of sleep is what mostly affects our memory and learning abilities. Dreams are complex, but they may play a significant role in instructing the brain on which memories/experiences that have been collected during the day or are worth retaining, and which are useless and can be “forgotten”.

Sleeping, with all its stages, is a fascinating area of study, and researchers are finding out new informative ways to help us get a good night’s sleep every day. In the meantime, we wish you a good nights’ sleep and pleasant dreams.

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Expert Author : Kelly Everson (Consumer Health Digest)

Kelly Everson is an independent editor, an award-winning writer and an editorial consultant in the health and fitness industries. Currently, she is a contributing editor at Consumer Health Digest.