Stages of sleep

The Five Key Stages of Sleep

Understanding what goes on in our heads while we sleep has been a quest that goes back in time immemorial. Dreams have always taken on mystical qualities that tease, inspire and sometimes haunt us. And while there is still much to be learned about the meaning of dreams, scientists have gained a better level of understanding of the stages of sleep and how important they are to our health and well-being.

During a full night of sleep, your body experiences five distinct and quite different stages. The first 4 stages fall under the Non-REM stage and the last stage, is a REM stage. REM stands for Rapid Eye Movement, which is the most easily recognized feature by an outside observer.

Stage 1
This is the lightest sleep stage and only lasts a few minutes. Muscle tone relaxes and brain wave activity begins to slow down. You may also get the feeling that you are falling (hence the phrase ‘falling asleep’. Many people experience jerks or abrupt muscle spasms which may cause them to jump suddenly. This is called Hypnic myoclonia.

Stage 2
This is the first defined stage of Non-REM sleep, where your body prepares itself for deep sleep. Your heart rate slows down, and your body temperature decreases. Here the brain produces spikes in brainwave activity known as spindles. These are believed to play a role in consolidating long term memory and sensory processing, forming most of our memories. At this important stage sleep should not be interrupted.

Stage 3 & 4
This deep sleep stage is the most intensive and restorative stage of sleep. The body muscles are fully relaxed, breathing, blood pressure and body temperature decreases significantly. The body continues to produce growth hormones, regulates immune function and repairs and recovers cells. Sleep walking is also known to occur during this stage.

Stage 5
This is the REM, Rapid Eye Movement state, which is an active sleep state. It is believed the REM state plays a vital role in your brain’s ability to learn and remember, as it is in this state that the brain processes and stores information. You typically dream during the REM state of sleep. Muscle paralysis sometimes occurs, which scientists believe is a built-in protective measure to keep one from injury and acting out our dreams.

As we grow older the timing and duration of our sleep cycles change. Some individuals have longer sleep cycles with less time in REM and others have shorter ones with longer REM, similar to what babies experience.

To increase your chances of a good night’s sleep, avoid substances such as caffeine that disrupt sleep cycles, especially when consumed too close to bed time, as this will make it harder to fall asleep. Alcohol, on the other hand, may help you to fall asleep easily, but will ruin the second half of your nights sleep as the body starts to process the alcohol, which begins to act as a stimulant.

Follow our Better Sleep Tips for more information.

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