Tuesday, July 5, 2011

Five Stages of Sleep

Most people think of sleep as a period of inactivity for your body and brain. You close your eyes, your brain disconnects, and you float off for 8 hours of refreshing, passive rest.

But the truth is, while sleep is how we refresh our bodies, the act of sleeping is anything but passive!
In fact, you're not aware of it while it's happening, but as you sleep, your body and brain go through five different - and very active - stages.

During these five stages, your brain activity changes, your body temperature fluctuates, and your body goes to work repairing your cells, tissues, and muscles, refreshing your body, and preparing your brain for your next day.

These stages (known collectively as "sleep architecture") follow a predictable pattern over the course of a typical 8-hour period of sleep.

Here's how they work:

Stage One: During Stage One of your sleep cycle, you hover between being awake and being asleep. During this stage, your brain produces "theta" waves, which are very slow brain waves. If someone were to wake you up during this first stage, you may feel like you hadn't been asleep at all. Stage One lasts for approximately 5 to 10 minutes.

Stage Two: The second stage of sleep, which lasts for about 20 minutes, is when your brain begins to produce quick, rhythmic brain wave activity known as "sleep spindles." During this stage, your body temperature begins to drop, and your heart rate begins to slow.

Stage Three: This is the stage at which you begin to transition from light sleep to a much deeper sleep. During this stage, your brain begins to produce slow brain waves known as "delta" (higher amplitude, lower frequency) brain waves, and your heartbeat and breathing are at their slowest.

Stage Four: Many scientists refer to this fourth stage of sleep as "delta sleep," because this is the stage during which your brain produces significant delta waves. During this deep sleep, which lasts about 30 minutes, your blood pressure drops and muscles relax, though blood flow to muscles increases. Stage Four is the most restorative sleep, when your body releases hormones for growth and development, repairs tissue, and refreshes energy.

Stage Five: Also known as "rapid eye movement "(REM) sleep. REM sleep is the stage where you have the most brain activity of all sleep, with brain waves that often resembles those you have when you're awake.

REM sleep is characterized by movement of your eyes, increased breathing, increased brain activity, and relaxation of your muscles. Most of your dreaming is done during this stage.

During REM sleep, your brain processes what you've learned that day, strengthens your memory, and refreshes its supply of critical chemicals like serotonin and dopamine, which help with your mood the next day.

What's most interesting about the five stages of sleep is that they don't occur in order.

You begin sleep with Stage One, and then progress through Stages Two, Three, and Four. But instead of going on to Stage Five (REM) sleep right away, you go back to Stage Three, then Stage Two, and then move on to REM sleep.

Once your REM sleep is over, you typically go back to Stage Two, and start the cycle over again.
During the course of a typical night, you go through this full cycle of stages about four or five times. But with each cycle, Stage 5 lasts longer, so by the final cycle of your nightly sleep, you may be staying in REM sleep for up to an hour.

So rather than a period of inactivity or "down time" for your body, sleep is actually a highly complex and active period, during which your brain works to repair and restore all of your body's systems, as well as get you ready for your next day.

With such critical processes taking place, one thing is clear:  getting a good night's sleep every night is of utmost importance for your continued good health and mental well-being.

Article courtesy of the Alteril website

*This information is for educational purpose only. It is not meant to diagnose or cure a disease.

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