Brain Basics
Stages of Sleep
Dream Science
Types of Dreams
Dream Disorders
100

This is the body's main control center, made of billions of neurons.

What is the brain?

100

During sleep, the brain does this to remove unnecessary information and prepare for new learning.

What is processing/cleaning?

100

Dreams are a mix of images, sensations, and emotions that occur during this.

What is sleep?

100

In this type of dream, the dreamer becomes aware they are dreaming and can control what happens.

What is a lucid dream?

100

In this disorder, people physically act out their dreams because normal muscle function during REM fails.

What is REM Sleep Behavior Disorder?

200

The brain is protected by this structure made of 22 bones.

What is the skull?

200

This sleep stage is when most intense dreaming occurs, with high brain activity.

What is REM sleep?

200

Dreams can last from a few seconds to this long in minutes.

What is 20–30 minutes?

200

These disturbing dreams cause fear or anxiety and often wake the dreamer up.

What are nightmares?

200

Unlike nightmares, people who experience these intense sleep episodes usually have no memory of them afterward.

What are night terrors?

300

This is the largest part of the brain, responsible for thinking, feeling, and remembering.

What is the cerebrum?

300

In non-REM sleep, this stage involves slower brain waves with occasional bursts of rapid activity.

What is Stage 2?

300

Dreams are sequences of these four things that occur randomly in the mind during sleep.

What are images, sensations, emotions, and thoughts?

300

These dreams repeat over time with similar themes and are often linked to unresolved conflicts.

What are recurring dreams?

300

Night terrors typically occur during this stage of sleep.  

What is non-REM sleep?

400

This part of the brain controls balance and coordination.

What is the cerebellum?

400

REM stands for these three words.

What is Rapid Eye Movement?

400

Ancient Egyptians and Greeks believed dreams were these — messages from a higher power.

What are divine messages/prophecies?

400

This type of "dream" happens while you are awake and conscious.

What is a daydream?

400

Night terrors are more common in children but can also affect these people.

Who are adults under stress?

500

This part of the brain acts like "autopilot", controlling breathing and heart rate.

What is the brain stem?

500

REM periods get longer as the night goes on, so dreams are most memorable during this time of day.

What is the morning?

500

This word from the lesson means feeling completely surrounded by an experience, like being inside a 3D movie.

What is immersive?

500

Nightmares can be triggered by stress, trauma, or these.

What are certain medications?

500

In REM Sleep Behavior Disorder, sleeping people may do this, which could injure themselves or others.

What is physically acting out dreams?

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