Understanding the Stages of Sleep

Curling up in your bed after a long day of work is one of the greatest feelings in the world, but for many, nighttime is synonymous with restlessness and irritation. According to the Sleep Health Foundation, around 33% of people suffer from mild to severe insomnia.

Scientists have spent a long time studying and observing sleep patterns, and the American Sleep Association has categorized it into five stages. The first four stages are considered non-REM sleep and the final stage is REM sleep. If you have trouble falling asleep or staying asleep through the night, contact the best insomnia doctor in New York by speaking with Dr. Shukla at Sleep MD.

What Is REM and Non-REM Sleep?

Sleep may seem like your body is in a passive state, but scientists have discovered long ago that your brain is quite active while sleeping. In fact, Harvard Medical School did a study that showed your brain is sometimes more active while asleep than when awake. REM stands for rapid eye movement and is appropriately named because once you enter this final stage of sleep, your eyes literally move rapidly.

Non-REM sleep refers to the stages that lead to you entering REM sleep. The Non-REM stages last approximately 90 minutes before your first REM cycle starts. If you are interested in learning more about your sleeping cycles, Sleep MD can discuss this further with you because they are the best insomnia doctors in New York.

Stage 1

This is the lightest stage of sleep, and is essentially the time when you get drowsy and are entering sleep. This stage only lasts 5 to 10 minutes, and is when you begin to have a decrease in your heart rate and breathing. You can easily be woken from this stage without any repercussions. Many of us have also experienced body twitches, or “hypnic jerks”, during this stage, which is where your body has a brief spasm, like a falling sensation.

Stage 2

Essentially, stage 2 is just a slightly deeper version of stage 1, where your body becomes more relaxed. This stage lasts a bit longer than the first at 10 to 25 minutes.

Stage 3 and Stage 4

Until 2007, these two stages were considered separate cycles of the sleep progression, but are more commonly referred to as one stage now. Some doctors still differentiate between these final two stages of non-REM sleep, but the physiological difference between the two are almost indistinguishable. These two stages are characterized as even deeper sleep than the previous two, and are commonly called “Slow Wave Sleep.” This stage typically lasts 20 to 40 minutes and is necessary to feel refreshed the next morning. Being awoken from this stage creates sleep inertia, which is a fancy way of saying you will feel groggy for an extended period of time after waking up. Because of this phenomenon, it is suggested to nap only for 30 minutes or less, so that you do not enter this stage of sleep and become affected by sleep inertia. This stage also exhibits the lowest levels of breathing and heart rate, and is accompanied by a decrease in blood pressure and body temperature. Sleepwalking, sleep talking, and night terrors have all been linked to this stage.

Stage 5

This is the final stage of sleep and is the only stage where REM occurs. Doctors have long speculated why our eyes rapidly move during this phase of sleep, and have concluded it is most likely linked to dreaming. Even though there is no definitive answer, it seems like an appropriate hypothesis given that this is the only stage of sleep that we can dream. While the other four stages were a progressive process into relaxation and rest, this stage exhibits faster breathing and brain activity. This is the time of night where the brain processes information, which is why it is common to dream of the previous day’s occurrences.

Even though the muscles in your body do not move during REM sleep, the brain waves are like when we are awake. Many doctors have theorized that this occurs in order to protect us from injury while we sleep. With our brains working so feverishly, it would be dangerous if our muscles followed suit.

Sleep is a time that we associate with rest and refreshment, but scientifically, it is a time that our brain is working just as much as during the day. Sleep is imperative to stay focused, so be sure to contact the best insomnia doctor in New York, Dr. Shukla, if you have any questions or concerns about your sleeping habits.

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