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PIECES OF MIND: What's in a Dream?

What happens when we sleep, and why, are questions that intrigue scientists and laypeople. Two scientists -- Robert Stickgold of Harvard University and Carlyle Smith of Ontario's Trent University -- invite viewers to spend some time in their sleep labs, along with Alan Alda. Their sleep experiments help illuminate what goes on in our minds while we're dreaming. Stickgold's research looks at what happens during REM (dream) sleep, while Smith explains why.

Curriculum Links
"To Sleep, Perchance to Dream..."
Activity 1: The Sleep Journal
Activity 2: Sleep and Dreams in Our Culture
What Happens When You Sleep
For Further Thought




brain organization,
nervous system

scientific method


mental heath



data analysis






The scientists you see in this episode of SCIENTIFIC AMERICAN FRONTIERS are researching what seems to be an inherent human fascination with sleep and dreams. With modern technology and new tools for unlocking "Sleep's Dark and Silent Gate" (title of a song by Jackson Browne), scientists have extended and are redefining some of our understanding about sleep and dreams. Recent findings have implications for learning. In these activities you will explore more about sleep and dreams.


Although you can't measure changes in brain chemistry or track subtle variations in an electroencephalogram (EEG) to study REM sleep, you can use one of the tools sleep and dream scientists have used for many years: the sleep journal. By keeping a sleep journal, you can track your sleep patterns to see if the quantity and quality of your sleep affects your performance in school or sports. A sleep journal also allows you to record your dreams and consider their content to see if they relate to events during your waking hours.

Keep a journal to track sleep and dream activity.

To keep a sleep journal you must get into the habit of writing down information at three key times: when you go to bed, when you wake up during the night and when you wake up in the morning. (You may adapt the study and track just your nighttime and morning routines.) Establish a time period for your study (one week is suggested). When you have completed the study, examine your data and answer the questions that follow. Summarize your findings.

  • As you go to bed.
    Write down the date, the time you go to bed and key events that happened to you during the day. Note your resting pulse rate. Later you will use this information to determine the total time you slept, how well you slept and if the day's events seem to have influenced your sleep patterns and dreams.

    When you wake up at night.
    Often when you wake during the night it is right after a period of REM sleep and therefore, most likely, right after a dream. It is better to try to recall any dreams and write them down when you wake up rather than to turn over and figure you'll remember to write them down in the morning. When you wake at night, write down the time. If you recall a dream, write down as many details as you can remember. (Hint: keep a notepad, pen and flashlight by your bed.)

    When you wake up in the morning.
    Write down the time you wake up, the number of hours you slept and whether you feel rested or still tired. Record your pulse when you wake up and compare it with your resting pulse from the night before. This data gives you an idea about how well your sleep has helped you recover from the previous day's exertions. Scientists believe that deep sleep has a critical restorative effect on the body. In general, if you slept well, your pulse should be lower in the morning than it was the night before. Lastly, record any dreams you remember from the night before.

  1. Do the previous day's activities seem to interfere with your ability to get a good night's sleep? If you go to bed worried, does that cause you to have a restless night's sleep?

  2. Do your dreams seem to be related to what happened during the previous day? What other factors might affect your dreams -- worries, experiences, people you've met or seen on TV?

  3. Do the number of hours and the quality of your sleep -- whether you are rested or still tired when you wake up -- seem to affect how well your day goes? Does a good night's sleep help you have a better day?

  4. Is there a difference in your ability to recall details of dreams recorded when you wake up at night versus those recalled in the morning?

  5. Does your ability to remember your dreams seem to improve as you track them in your journal?

  6. Do you notice a change in your ability to solve problems or think creatively after a good night's sleep?


Dream and sleep images are everywhere in popular culture. You can probably think of many references to sleep and dreams in movies, TV shows, books, poetry and songs (Sheryl Crow's album Ordinary Morning contains allusions to sleep and dreams, for example). Going back in time, Shakespeare used many references to dreams, such as these lines from Romeo and Juliet: "True, I talk of dreams; Which are the children of an idle brain."

Find examples of ways sleep and dreams are used as images in popular culture.

Divide into teams and list as many movies or songs as you can think of that use sleep or dreams as part of their imagery. Be as specific as possible and write down the exact title of the song or movie, and the lyrics in the song or scenes in the movie that use these images. Explain what the songwriter or screenwriter was trying to say.

  • Find additional references to dreams and sleep in cartoons, books, advertisements, etc.
  • Look for examples of dream images and what they might convey in works of art, like paintings by Marc Chagall.
  • Dreams play different roles in various cultures. Consider the concept of dreamtime in the mythology of Australian Aborigines or the dream catchers of Native Americans.


An EEG (electroencephalagram) shows what happens to our brains during sleep. Most people experience several stages of sleep during an ordinary night. If you were to spend the night in a sleep lab connected to an EEG like the subjects do on FRONTIERS, the EEG would give a portrait of your brain during the night. The electrical activity indicated by brainwave patterns would fluctuate through stages of non-REM and REM sleep.

Sleep cycles through five stages:
  1. Stage 1: This "alpha" stage is the transition from wakefulness to real sleep.

  2. Stage 2: Generally considered the first true sleep state and still light sleep.

  3. Stage 3: Characterized by deep, slow-wave sleep. Stage 3 might be described as moderately deep sleep and Stage 4 as very deep sleep.

  4. Stage 4: Also characterized by deep, slow-wave sleep. In Stage 4, the "delta" stage, is restorative sleep and can be affected by caffeine, drugs, noise, etc. People with sleep-related disturbances or sleep deprivation show a lack of Stage 4 sleep.

  5. REM sleep: In the 1950s, scientists discovered that the eyes of sleeping subjects fluttered back and forth under their eyelids at various times. They identified this stage as rapid-eye-movement or REM sleep. As you see on FRONTIERS, REM sleep plays a role in the consolidation of memories and processing information. So "sleeping on it" may serve a vital function in problem solving for humans. In addition, many great discoveries in science and other creative endeavors have been initiated by dreams.

Humans spend about 30 percent of their sleep time dreaming and about 20 percent in deep sleep, with the remaining time in light sleep. Perhaps you can observe a sleeping dog to see if it shows rapid eye movements.


  • It is estimated that millions of Americans -- especially teenagers -- experience sleep deprivation. What has contributed to this phenomenon in our culture? Consider the impact on driving, learning, and jobs. Are you getting enough sleep?
  • Scientists believe that REM sleep helps consolidate memories. What implications does this have for learning?
  • Some chronic diseases are associated with either a loss of Stage 4 sleep or some form of sleep disturbances. Use the Internet to find out more about current research into sleep disturbances like narcolepsy, sleep apnea, insomnia.
  • Why did early humans fall into the habit of sleeping at night?

CREDIT: These activities were contributed by Jamie Larsen, a science teacher and Tufts University Wright Fellow currently living near Sedona, Arizona.


Scientific American Frontiers
Fall 1990 to Spring 2000
Sponsored by GTE Corporation,
now a part of Verizon Communications Inc.