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The Stages of Sleep


REM Sleep


Paradoxical Sleep


During REM sleep (paradoxical sleep) our brain is not resting but extremely active. Brain waves are small and fast with bursts of activity. The body is more active with pulse rate increasing and
fingers and toes twitching. However the main part of the body is paralysed, probably to prevent damage during dreams; waking during REM sleep can result in the unpleasant experience of sleep paralysis.
Sleep Cycle
REM sleep is characterised by "Rapid Eye Movement". Even though the eyes are closed it is possible to see this movement taking place under the eyelids. REM sleep is believed to be the phase when we dream most often and most intensely. (Though dreams do
also occur at other stages of sleep).

In infants, REM Sleep is sometimes called "Active Sleep".

The Cycle


After REM sleep, the sleeper sometimes wakes briefly then returns to the early non-REM stages and the stages of sleep cycle repeats.

The length of the cycle and the relative lengths of the four stages of sleep varies a lot between individuals. Babies tend to spend a lot of their time in REM sleep - up to 50%. In adults this is usually
a lot less - around 20% to 25%. The amount of time spent in deep sleep (NREM 3 and 4) also decreases as we age and some people eventually get little if any deep sleep.

The cycle length also changes for an individual over the course of a single night. During the first cycle an adult will usually stay in REM sleep for around ten minutes. In later cycles during the night we get more REM sleep and less deep sleep. This is possibly our body prioritising "physical" repair over "mental" in case sleep is limited.

Sleep is clearly a lot more complex than just "switching off"!

IMPORTANT NOTE: This is not a medical site. You should always discuss medical matters
with your doctor.

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