Part three in a five part series
Part I: The Land of Nod…Why should we go? | Part II: The Dark Ages
There is a lot more to sleep than meets the eye.
During the night we pass through five distinct phases of sleep which repeat through the night. On average a complete sleep cycle takes between 90 and 110 minutes. The first sleep cycles each night contain relatively short Rapid Eye Movement (REM) periods and long periods of deep sleep.
As the night progresses, however, REM sleep periods increase in length while deep sleep decreases.
| Light sleep | In Stage 1 we drift in and out of sleep and can be awakened easily. If someone is watching you in this stage they would note slow eye movement and low muscle activity. If you have ever experienced sensations of falling or weird muscle jerks in your sleep then you have been in this stage. |
In Stage 2 we are preparing for deep sleep. Our temperature drops and our heart rate slows. Scientists notice that our eye movement also stops and brain waves become slower with occasional bursts of rapid waves, called sleep spindles. | |
| Deep Sleep | In Stage 3 brain waves become very slow (called delta waves), begin to appear interspersed with smaller, faster waves. It is very difficult to wake people in this stage of sleep. It is during this stage that a person may experience sleepwalking, night terrors, talking during sleep, or bedwetting. |
In Stage 4 the brain produces delta waves almost exclusively. It is very difficult to wake in this stage and if forced awake we feel quite disoriented. | |
| REM Sleep | Stage 5 is the dream stage. Our brain activity is very similar to when we are fully awake and our eye movement is rapid. We experience several REM sleep stages each night. |
You will notice as the night progresses, REM sleep periods increase in length while deep sleep decreases. By morning, people spend nearly all their sleep time in stages one, two, and REM. The first REM sleep period usually occurs about 70 to 90 minutes after we fall asleep.
Good night, sleep tight, hope the bed bugs don’t bite!
– Kim
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