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NOVA scienceNOW: Sleep

Viewing Ideas


Before Watching

  1. Record information about sleep habits. Starting the week before you view the program, have students record four kinds of their own sleep-related data—hours of sleep, general mood, physical energy, and mental alertness. Ask them to record the data for a five-day period and enter it in bar graphs on the Why Sleep Matters graphing sheet.

    After five days of data collecting, have students form groups and discuss their logs. What was the average number of hours each person slept per night? How does this compare to what doctors recommend (between nine and ten hours)? Was there a common pattern in relation to daytime alertness/sleepiness? Have a recorder from each group make a list of common findings. Then have groups share their results with the class.

    As an extension, have students also record the following information about their sleep behavior and discuss it when they meet in groups:

    • The time they went to bed and got up the next morning

    • A general statement about how they slept, and possible reasons for their good or poor night's sleep

    • A log of their level of alertness/sleepiness, in which they record every two hours during the day how alert/sleepy they feel, using a scale of one to five (one equals least sleepy, five equals most sleepy).

  2. Play a game to review sleep-related vocabulary. Have students play the word game Choose the Correct Meaning to familiarize them with vocabulary terms related to sleep and memory. Divide the class into three or four teams. Read a vocabulary term and the three possible definitions aloud. Have teams take turns identifying the correct definition for each term.

  3. Design a poster about sleep. Divide the class into four groups and have each group research the questions below and present their work in a poster. (You may choose to have groups present information in a health-brochure format.) See the Links and Books section for sources of this information.

    • What are rapid eye movement (REM) and non-rapid eye movement (NREM) sleep? What are the differences between these two types of sleep?

    • What is the body's biological clock? Why is it beneficial to stay on a set sleep schedule? What are the sleep requirements for people of different ages?

    • What is sleep debt? What kinds of activities are affected by a lack of sleep?

    • What are some common sleep disorders?

    (Suggested source:

After Watching

  1. Make a model of the human brain. Have student teams make a clay or Plasticine model of the human brain. (Or, provide students with a diagram of the brain for this activity.) The program highlights two brain regions, the hippocampus and the neocortex, where nerve cells show coordinated activity during sleep. As students make the brain models, have them use bright colors to indicate the hippocampus and the neocortex. Ask teams to label the different regions of the brain using toothpicks with labels attached.

    Have students research and then write on an index card the basic function of each region of the brain. (Include frontal, temporal, and parietal lobes, the cerebellum, and the brain stem. The hippocampus is in the temporal lobe. The neocortex is the top layer of the frontal, temporal, parietal, and occipital lobes.)

    (Suggested sources: and

  2. Play a game demonstrating how information storage relates to memory. Researchers have shown that long-term memories are embedded in a web of neural connections. Individual memories aren't stored as distinct "files," separated from all others. Rather, many connections exist among a person's memories. To demonstrate this phenomenon, read aloud a list of eight unrelated words, such as tub, grass, car, ring, chair, cow, juice, and star. Then have students write down as many words as they can remember. As a class, list the words. The class will likely be able to recreate the list of eight words, but individuals are less likely to get them all. Next, read, in a mixed-up order, an eight-word list that contains four pairs of closely linked words, such as eye, nose, boy, girl, apple, orange, salt, pepper. Again, have students write down as many words as they can remember. When recalling the list, most students will write related words together because such words are strongly connected in people's long-term memory network or web.

    Another way our brains remember information is by grouping it in meaningful "chunks." In the above example, students remember four pairs, or chunks, rather than eight individual words. To retest "chunking," ask students to see how well they can remember the next group of clustered letters: THEB IGDO GCHA SEDT HOSE ORAN GECA TS. Then regroup the letters: THE BIG DOG CHASED THOSE ORANGE CATS and have students explain why the second group was easier to remember. (A sentence is like one chunk of information. All the words in the sentence are familiar. The brain makes an image of the sentence.)

  3. Play games that test short-term memory. The program discusses how sleep may help the brain process short-term memories. Have students brainstorm the definition of a short-term memory (a memory of an event that lasts from several seconds to a few minutes). Then divide the class into groups and have each group play the following three short-term-memory games. Conclude with a class discussion about why seeing something multiple times might reinforce memory. (Neural connections may be enhanced.)

    What's on the Tray?
    Materials for each group: tray, 25 different common items, towel

    Procedure: Provide each group with a covered tray of items. Have each group remove the cover, observe for 25 seconds, and then cover the tray again. Individual students should write down all items they remember. Try the game a second time. Have groups share general results. The hypothesis is that students will remember more after two trials because their initial observation was reinforced by the second viewing. Do the class data support this hypothesis?

    What Was Taken?
    Materials for each group: tray, 25 different common items, towel

    Procedure: Provide each group with a tray of items. Have students observe their tray for 25 seconds and then close their eyes. Ask a designated member from each group to remove one item from the group's tray. Then each person tries to identify what's missing. Repeat the game a few times.

    Again, have groups share results. Were students better able to discover which item was missing after the second or third trial?

    Which Cities?
    Material for each group: a story that is a few paragraphs long containing the names of 5 to 10 well-known cities. You may choose to write a story about a class trip, a sports event, or a student discussion related to traveling.

    Procedure: In each group, one person reads the story aloud while the others listen. When the story is finished, group members should try to list the names of the cities in the story. Repeat and see how much difference a second reading makes.

  4. Hypothesize some reasons why sleep may be important for different kinds of animals. Researchers have found that even fruit flies need sleep. Sleep is important for our survival, and for some animals, it seems be important to learning and memory. Provide students with the information in the first two columns of the table below. Do students see any patterns? Then have the class hypothesize some reasons why sleep may be important for different kinds of animals. (Be sure to let students know that only a few different types of animals have been subjects in laboratory sleep and memory studies. Students are only proposing hypotheses. Accept reasonable answers.)


    Average Daily Amount of Sleep

    Sample Hypotheses for the Role Sleep Might Play in Consolidating Memory

    Brown bat

    19.9 hours

    To process routes they travel, finding food, and avoiding predators

    Human infant

    16.0 hours

    To process new information from the surroundings


    14.9 hours

    To process where food is located and hidden


    12.1 hours

    To process strategies for capturing food and prey


    11.4 hours

    To process location of food and ways to avoid predators


    10.6 hours

    To process social and training experiences

    Bottle-nosed dolphin

    10.4 hours

    To process their songs


    9.7 hours

    To process social interaction and locating and accessing food

    Human adolescent

    9.3 hours

    To process social interaction and learning experiences

    Human adult

    8.0 hours

    To process social interaction and learning experiences


    3.5 hours

    To process social interaction and locating food and water


    1.9 hours

    To process memories related to location of food and water

    Data for animal sleep times obtained from:

  5. Learn about "daily rhythms" by performing an activity measuring reaction time. While the segment considers the role sleep may play in learning and memory, many factors can affect performance. For example, most living organisms follow a circadian rhythm, an "internal body clock" that regulates a roughly 24-hour cycle of biological processes. Yet even with such a biological "clock," there is variation in people's daily rhythms, with different people experiencing such things as hunger, maximum alertness, and tiredness at different times of the day. People often acknowledge these differences by describing themselves as early birds or night owls.

    Explore students' circadian rhythms by having them identify the time of day they experience their peak performance. Have them brainstorm some of factors that might affect performance, such as when a person last ate, one's mood, the time of day, and events that occurred that could interfere with the ability to focus. Ask, "How do you think time of day influences our actions and behavior?" (Some people are more alert, feel better, and perform better during the morning; others during the evening.) Tell students that these time-of-day changes are called circadian rhythms, and they contribute to how we perform and feel throughout the day.

    Have students rank themselves as an early bird or night owl, based on what they think are their times of highest alertness. (Early birds are most alert before noon and night owls are most alert during the evening.) Discuss the Student Reaction Time Activity below, and either copy the procedure onto the board or onto a handout. Give each student four pieces of grid paper, and do the first trial in class. Ask students to complete the remaining three trials before the next class meeting.

    Student Reaction Time Activity

    Materials: Reaction Time Chart, 4 sheets of 1-cm grid paper, pencil, timer (seconds and minutes)

    Procedure: On the Reaction Time Chart, mark whether you are an early bird or a night owl. Set the timer for one minute. Start the timer, and mark as many grid-squares as possible with a check mark. After a minute, count the number of squares checked. Record your results in the chart.

    Reaction Time Chart

    I think I'm more of: ___an early bird ___a night owl

    Time of Day

    Number of checkmarks

    Early morning


    Mid morning


    Around dinnertime


    At bedtime


    Before the next class period, make a class-data chart on the board like the one below. Have students share their results by placing a check in the space that matches their designation and the times of their highest and lowest scores. Once the chart is complete, have students see if the data supports the idea that performance is influenced by time of day. Emphasize that one's circadian rhythm impacts alertness and, therefore, learning, memory, and performance. Have students brainstorm how a person's circadian rhythm could play a role in activity choices (e.g., playing games late at night or playing sports early in the morning); work or career choices (e.g., being an emergency-room surgeon or an air-traffic controller); and personal choices (e.g., whether one gets sufficient sleep). Also ask about what people can do to make adjustments when their school or work schedules conflict with their natural rhythm (e.g., take naps). End the discussion by brainstorming variables that may have influenced the activity results. (Students may have experienced different stressors, amounts of sleep, or levels of nutrition.) Have students suggest controls that would make the investigation more reliable. (Some students may suggest keeping participants in a more uniform environment that would better control sleep, stress, and diet.)

    Time of Day



    Place an "X" when you got your highest score

    Place an "X" when you got your lowest score

    Place an "X" when you got your highest score

    Place an "X" when you got your lowest score

    Early morning





    Mid morning





    Around dinnertime





    At bedtime





Links and Books

Web Sites

NOVA scienceNOW
Offers sleep-related resources, including additional activities, streamed video, and reports by experts.

Are You a Lark, an Owl, or a Hummingbird
Presents an excerpt from a book about daily rhythms and the body clock.

Clockwork Genes
Contains four animations on biological clocks, pertinent articles, and an online biological clockworks exhibit.

Information about Sleep
Includes information about the sleep cycle, sleep requirements, the function of sleep, and sleep disorders.

Neuroscience for Kids
Provides a variety of memory-related experiments.

Power Nap Prevents Burnout; Morning Sleep Perfects a Skill
Summarizes "power nap" and sleep studies that suggest sleep enhances some types of learning.

Researchers Find the Snooze Button
Describes research using fruit flies which considers the role of "mushroom bodies" on regulating sleep.

Sleep Forms Memory for Finger Skills
Describes results of a finger-to-thumb motor skill task. Findings indicate that sleep is important for consolidation of motor skill memories.


The Body Clock Guide to Better Health
by Michael Smolensky and Lynne Llamberg. Henry Holt and Co., 2000.
Discusses the importance of body rhythms in relation to health.

The Promise of Sleep
by William C. Dement and Christopher Vaughan. Dell, 2000.
Describes sleep disorders and discusses the importance of sleep.

Teacher's Guide
NOVA scienceNOW: Sleep

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