Everyone sleeps and everyone dreams.  This is a fact.  It’s easy to know why we sleep – our bodies need rest – but why do we dream?  Researchers believe they have answers to this question.  They say that while we are awake, going through our day, we have new experiences.  Some of these experiences we want to keep as memories, but most of them are not important, so we need to forget them to make space for new memories.  Our dreams allow us to do this.

When we sleep, we have two different dream states.  The first is called “slow wave sleep” or SWS.  In this dream state, our hippocampus, the part of the brain where our day’s experiences are stored, sends all that information in short and very fast bursts to a different part of our brain called the frontal cortex.  Then the hippocampus shuts down to allow a second dream state called “random eye movement” or REM, which gets its name from the fast eye movement under the eye lids that happens in this dream state.  In these dreams, which seem like real-time movies, the cortex plays back information from the hippocampus along with other memories that are stored in the brain and determines if the new information is useful or useless.  We save the useful information and discard the useless.  REM dreams happen every 90 to 100 minutes and we have 3 to 4 of them every night.  Also, they last longer and longer as the night goes on.  The last REM dream can last as long as 45 minutes.  Researchers say that if there’s strong emotion connected to a memory, then it is usually stored and remembered.  Although our brains are very active during REM sleep, our bodies are paralyzed so that we don’t act out our dreams.  To have an effective night of sleep, we need a balance of SWS and REM dream states.  Although our brains are active at night, by morning most people don’t remember their dreams.

Click on the audio recording below to hear the lesson.

Vocabulary:

researchers:  people who study things to find answers
experiences:  situations that teach us something
states:  conditions, kinds
bursts:  instances of high energy.
shuts down: turns off
random:  with no order or regularity
stored :  kept
determines:  decides
discard:  throw away, get rid of
last:  continue to be
emotion:  feelings
paralyzed:  unable to move
act out:  do what we’re dreaming
effective:  good for you
balance:  equal amount

Pronunciation Exercise:  Listen and repeat the above vocabulary on the audio file below.

© 2014 Ambien Malecot