Rapid eye movement facts for kids

Sleep is super important for all mammals and birds. It's like a reset button for your body and mind! Scientists divide sleep into two main types. One type is called REM sleep, and the other is NREM sleep.

REM stands for Rapid Eye Movement. This is because your eyes move quickly back and forth under your eyelids during this sleep stage. Most of your dreams happen during REM sleep. These periods of REM sleep happen several times throughout the night. They usually get longer in the second half of your sleep. Scientists first discovered REM sleep in 1952-1953. Professor Nathaniel Kleitman and his student Eugene Aserinsky first linked these eye movements to dreams. Other researchers like William Dement and Michel Jouvet also helped us understand REM sleep better.

The other type of sleep is called NREM sleep. NREM means Non-Rapid Eye Movement. During NREM sleep, your eyes don't move quickly. You usually don't dream much during this time. NREM sleep has three or four different stages.

Stages of NREM Sleep

• Stage I: This is very light sleep. It's like you're just starting to doze off. You can wake up very easily from this stage.
• Stage II: This is also light sleep. Most adults spend about half of their total sleep time in this stage.
• Stages III and IV: These are called deep sleep stages. Deep sleep is super important for your body to grow and heal itself. It can be quite hard to wake someone up when they are in deep sleep. Sometimes, stages III and IV are grouped together and just called Stage III.

How Sleep Cycles Work

Adult humans usually sleep in cycles. Each cycle lasts about 90 to 110 minutes. A full night's sleep can have four or five of these cycles. Each cycle usually goes through the stages in this order: Stage I, then Stage II, then Stage III (or IV), then back to Stage II, and finally, REM sleep. After REM, the cycle often starts over again.

Why Sleep is Important for Animals

Both birds and mammals have REM and NREM sleep. This suggests that these types of sleep developed a very long time ago. It happened before birds and mammals became separate groups in evolution. This shows that having REM and NREM sleep is a very old and important feature for animals with backbones.

REM Sleep and Dreams

REM sleep is strongly connected to dreaming. If you wake someone up during their REM sleep, they can usually tell you about their dreams. About 80% of people can describe a dream if woken during REM. People woken from REM sleep often give longer and more detailed stories about their dreams. They also feel like their dreams lasted a long time.

Lucid Dreams

Lucid dreams are special dreams where you know you are dreaming. These types of dreams happen much more often during REM sleep. The things that happen in your mind during REM sleep often feel like real dreams. They usually have a story, feel very real, and can involve strong feelings.

Acting Out Dreams

Sometimes, people have a sleep problem called Rapid Eye Movement Sleep Behavior Disorder (RBD). This is when people physically act out their dreams while they are asleep.