|
DISCLAIMER
The material on this website is for your information only. Whilst we have taken all reasonable steps to ensure the accuracy and completeness of contents of this website, to the extent permitted by applicable law, the author accepts no responsibility for loss suffered as a result of any reliance on any part of its contents. Any medical information on this website is not intended as a substitute for informed medical advice. Dr Roger Allen is not responsible for the content of any linked site, changes or updates. Links are provided for your convenience. Inclusion does not imply endorsement. |
The Sleep Cycle
 |
The Sleep Cycle moves from Stage I to REM then it starts all over again, continuing throughout the night. Most people complete 3 to 5 cycles each night, each cycle lasts from 90 to 110 minutes. Towards the end of sleeping, the individual does not reach stages III or IV as the body prepares to wake up.
Non REM sleep |
Stage I |
Light sleep |
Eye and muscle activity slow |
||
Brain activity decreases by 50% |
||
Individual may experience sudden muscle contractions |
||
On this stage the individual and be easily aroused |
||
Stage II |
Eye movement stops |
|
Muscle activity stops |
||
Brain waves slow down |
||
Small burst of brain activity begin (also known as Sleep spindles) |
||
Stage III |
Deep sleep Starts |
|
Brain begins to produce slow delta waves |
||
There is no eye or muscle movement |
||
Stage IV |
Deep sleep |
|
Brain produces only delta waves |
||
No muscle or eye movement |
||
Hard to awaken |
||
REM sleep |
Heart and breathing rates increase |
|
Eye movement is quick and irregular |
||
Blood pressure rises |
||
Breathing becomes shallow |
||
Almost complete loss of muscle control |
||
Penile erections (males) and vaginal moistening (females) |
||
Sleeper begins to dream (more intense, vivid dreams) |
||
Interesting facts....
Rodents, hedgehogs, cats and lower primates sleep about two thirds of their lives. The echidna sleeps for about 8.6 hours out of 24 hours but has no REM sleep. |
 |
