NOVA scienceNOW: Sleep
Students practice a procedural
skill—knot tying—to investigate if and in what way sleep affects
learning and memory in relation to a learning a procedural skill.
Students will be able to:
learn the importance of
practice in developing a procedural skill.
understand that information may become more permanent following sleep.
make inferences about the effect sleep may have on
some types of memory and learning.
Review the investigation and consider how
controls strengthen the experiment.
- copy of the "Sleep and Memory?" student handout
- copy of the "Knot Tying with a Twist" student handout
- timer (seconds and minutes)
- rope (1 meter in length)
Sleeping is a behavior that is
natural and essential for our health and well-being. In fact, it is a
biological necessity—we would die without it. Still, sleep is not yet
well understood. It is known that sleep is not a time for all body systems to
shut down and rest. Some brain activity actually elevates during sleep, and
some hormone secretions increase too. Studies show that sleep affects energy,
reaction rate, coordination, concentration, and focus. Lack of sleep often
results in costly and even deadly consequences. Tens of thousands of people in
the United States are injured each year because of automobile accidents that
result from drivers' sleepiness!
Teens need between nine and ten
hours of sleep each night, and adults need about eight hours. In general, sleep
follows a predictable pattern or cycle of alternating phases of rapid eye
movement (REM) and non-rapid eye movement (NREM) sleep. The cycle begins with
about 90–100 minutes of NREM sleep followed by a period of REM sleep. The
pattern repeats itself, usually about five or six times each night, with
varying amounts (but within a predictable range) of NREM and REM sleep.
Different physiologic changes occur during the NREM and REM sleep; brain waves,
eye movements, and muscle tension also vary.
Scientists suggest that a
night's sleep (and sometimes even a nap) seems to help consolidate
memories related to habits, actions, and skills practiced during the day.
Research is beginning to reveal
more about the cognitive functions related to learning and memory that are
affected by sleep, and the brain regions involved. Scientists have found that
sleep seems to improve memory related to some types of declarative (learning
facts) and procedural (how to perform a skill) learning, as well as the ability
to accomplish some spatial tasks.
Memory pertains to the way
information is encoded, stored, and retrieved from our brains. Short-term
memory is related to storage and recall of
recent knowledge and events. Working
memory relates to the active aspect of
short-term memory. Recalling directions and gathering a remembered list of
items involve working memory. Long-term memory relates to the storage and retrieval of relatively
Investigators in the program theorize that during sleep,
the brain replays memories, modifying and enhancing them. Sleep helps improve
some kinds of memory tasks more than others, including recognition of visual
patterns, solving some kinds of math puzzles, and such skills as typing. In
rats, it seems that at least a part of the mechanism of memory enhancement
involves neural communication between two areas of the brain—the
hippocampus and the neocortex—both of which play a role in memory
In this activity, students will practice a procedural
skill, knot tying, and then investigate the effect of both practice and sleep
on learning this type of skill. Investigators in the program emphasize that it
is not only practice that makes perfect, but also a night's sleep!
Because it is difficult to perform
a highly controlled sleep experiment in a classroom, this activity is an
investigation of the possible role sleep plays in learning some types of
skills. After completing the lesson, students will analyze the activity and
suggest controls that could be included to improve the reliability of their
In the week before
doing this activity, ask three or four adults to learn the knots. Have them
assist students on the day the activity is performed.
Have students brainstorm and
share how they learned to perform skills such as typing, playing a musical
instrument, dancing, cycling, snowboarding, playing video games, or driving. (People
often learn these skills initially by being shown the skill by an expert and
then practicing it.) Ask students what,
other than practice, contributed to their learning the skill. (Some
students may say: talking to themselves about the process, mentally reviewing
the process, paying attention to mistakes, or thinking about and making
connections to other similar experiences. Some students may say that during the
process they thought about questions to later ask a teacher or friend whom they
thought might have the answer.)
Tell students that being actively
engaged in learning any of the above skills involves cognitive, or thinking,
processes—using their brains—coupled with physical movement.
After the discussion, you may choose to ask a few students
who have learned to play an instrument, perform a dance, or who have mastered
another skill if they would like to briefly demonstrate. Ask them how much they
practice and have them explain the difference between simple repetition and
thoughtful practice (see above). (You may want to demonstrate a skill
Ask students to
think about their own learning, and then have them identify factors that can
make it difficult to learn something (e.g., illness, injuries, stress, constant
distractions, not their best time of day to learn, lack of sleep). List the
factors on the board. Tell students that today's activity investigates
whether sleep plays a role in learning.
student with the materials listed in the Materials section. Review the
handouts. Ask students to pair up. Have pairs choose one of the three knots and
learn to tie it. Tell students that an adult can demonstrate tying the knot and
will help with any questions or problems. Each student should accurately tie
his or her knot five times.
On the "Knot Tying with a
Twist" handout, have students circle the knot they chose. After
accurately tying their knot five times, and before leaving class, partners will
time and score each other's knot tying, and then record on their
"Sleep and Memory" student handout, next to Trial 1, their knot
score and the time it took to tie their knot.
NOTE: Be sensitive to differences
in ability. Individual student scores and times may vary greatly. Each student
will be recording and tracking his or her individual results. When the class
analyzes the data, only common patterns will be discussed.
That evening before going to
bed, each student should test his or her knot-tying ability, writing the time
and score on the "Sleep and Memory" student handout next to Trial
2. A family member should assist, acting as a partner and timer.
When students wake up the next
morning, they should record on their "Sleep and Memory" handout the
number of hours they slept, how well they slept, and how rested they feel. (See
the Questions page of the handout.) Students should again tie their knot after
breakfast and record their knot-tying time on their "Sleep and
Memory" student handout, next to Trial 3. (Or, if class meets early in
the morning, have students repeat tying their knot in class, recording their
times and scores.)
Have students complete the rest
of the questions on their "Sleep and Memory" handout.
Draw two four-column charts on
the board with the following headings: Knot, Trial 1, Trial 2, and Trial 3.
(See activity answer, student handout question 3.) Have students enter their
data into one of the charts. Average the data for each knot and enter it in the
As a class, analyze the results
in the charts (first in the chart with the averaged data, then in the chart
with the whole-class results) by discussing knot times and comparing time
differences before and after sleep. Ask: "Is there a common pattern in
relation to time and score differences before and after sleep?" Have
students describe any pattern they see. Ask: "What role did practice play
in learning to tie the knot?" "Is there any evidence that indicates
sleep may have played a role in learning?" "Are there other factors
that may have influenced results?"
Then discuss students'
answers to the questions on the "Sleep and Memory" student handout.
As an extension, perform the
activity again but instead of knot tying have students explore the effect of
sleep on memorizing a short poem or speech. (Ask students to brainstorm a
learning activity to test.) Or try the same activity before and after a nap
rather than a full night's sleep.
Student Handout Questions
About how many hours did you
sleep last night? Answers will vary.
Check one of the following
- I slept
well, and I am well rested.
- I slept
somewhere in between well and poorly, and I'm somewhat rested.
- I slept
poorly, and I am tired.
Put your three knot-tying times
and scores in order, from least to greatest. Answers will vary. Typical
expected results for times: Trial 3 < Trial 1 ≤ Trial 2;
Typical expected results for
scores: Trial 2 ≤ Trial 1 ≤ Trial 3)
Results Chart (sample results)
Consider whether the times
suggest that sleep played a role in learning in relation to your knot-tying
ability. Knot-tying scores may be greater and times shorter after sleep What factors other than sleep may have influenced
results? Factors include simply the passage of time and being a
Describe the role that practice
played in helping you master your knot. Practice has the greatest influence
on learning. While practicing tying your
knot, what sorts of questions did you ask yourself? What thoughts did you have that
may have helped you be successful? Student responses may include
talking through the steps, reminding themselves about one or more difficult
steps, or remembering a helpful saying about the process.
Analyze the activity and suggest
controls that could be included to improve the reliability of results. Students
may suggest the following: control the sleep period as best as possible; choose
participants with the same amount of knot-tying or equivalent experience;
control diet; and control stress as best as is possible. Then, propose an experiment with additional
controls that would increase the reliability of the results. Students
may suggest that participants undertake the challenge together in an
environment that is as similar as possible for all participants.
Offers sleep-related resources,
including additional activities, streamed video, and reports by experts.
Are You a Lark, an Owl, or a
Includes information about the
sleep cycle, sleep requirements, the function of sleep, and sleep disorders.
Contains four animations on
biological clocks, pertinent articles, and an online biological clockworks
Information about Sleep
Presents an excerpt from a book
about daily rhythms and the body clock .
Neuroscience for Kids
Provides a variety of
Power Nap Prevents Burnout;
Morning Sleep Perfects a Skill
nap" and sleep studies that suggest sleep enhances some types of
Researchers Find the Snooze
Describes research using fruit
flies and the role of "mushroom bodies" on regulating sleep.
Sleep Forms Memory for Finger
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
The Promise of Sleep
by William C. Dement and
Christopher Vaughan. Dell, 2000.
Describes sleep disorders and discusses the importance of
The "Sleep and Memory" activity aligns with the following National
Science Education Standards (see
Science Standard C
Science Standard F
Science in Personal and Social Perspectives
Science Standard C
- The Behavior of Organisms
Science Standard F
Science in Personal and Social Perspectives
- Personal and Community Health
Classroom Activity Author
Developed by WGBH Educational Outreach staff.