When you sleep every night, without you even realizing it, your brain goes through five distinct sleep phases or stages: phases 1,2,3,4, and Rapid Eye Movement (REM) sleep. You complete one full sleep cycle when you pass through all five stages of sleep. Passing through these stages usually takes approximately 90 minutes, according to the National Sleep Foundation. Let’s take a look at each individual stage, shall we?
The first stage is characterized by light sleep. It’s also the stage between being awake and falling asleep. During this initial stage, you can be awakened rather easily. Your muscle activity slows down during this stage, as does your eye movement. Referred to as hypnic myoclonia, many people experience a jerking or sudden muscle contraction when in this stage.
Believe it or not, you spend almost half of your sleep time in the second stage of sleep. Here, your eye movements cease and your brain waves become slower. While your breathing and heart rate typical remain regular during this stage, your body temperature drops slightly. The latter is the reason why sleeping in a cool room is the best temperature for sleeping.
Stages 3 and 4 sleep phases constitute your deep sleep stages, with the fourth stage being more deep than the third. Known as delta sleep or slow-wave sleep, you may feel disoriented initially should you be awakened during these stages. If you dream during this stage, it can be fragmented. Your breathing slows and your blood pressure may drop during this phase. Because your energy is restored, tissue repair and growth occurs, and the blood supply to you muscles is enhanced, this stage offers the most restorative sleep. It’s also the stage that may be important to the strengthening of your immune system. During this stage, children sometimes experience night terrors, bedwetting, or even sleep walking.
For approximately 25 percent of your night, you experience REM, or rapid eye movement sleep. Most people enter REM sleep within 90 minutes of falling asleep. They, then re enter this REM sleep stage every 90 minutes thereafter. During REM sleep, your brain is active; thus this is the stage where you dream. Your eyes move rapidly back and forth, and your muscles are essentially “turned off” as your body becomes immobilized.
This phase is an important sleep stage as it helps support your data functioning and performance. Certain lifestyle choices, such as drinking alcohol and smoking cigarettes can decrease the amount of REM sleep a person receives. In addition, extreme cold or hot temperatures can disrupt REM sleep.
We need to go through these sleep phases each and every night to feel the most refreshed and alert for our day. REM sleep is also important for learning and memory, according to the National Institutes of Health. To get the most out of sleep, both quality and quantity are important. If your number of hours for sleep is cut short, your body doesn’t have adequate time to go through all the stages of sleep necessary for muscle and tissue repair or energy restoration.
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