Sleep Patterns

Shift workers adjust their sleep cycles, often resulting in sleep deficits.
Courtesy of the DOD/Petty Officer 1st Class Spike Call.

Grades:
Length: Variable

Overview

All mammals, including humans and many other kinds of animals, need sleep. Most people have regular patterns of sleeping and waking times. In this lesson, students collect information about their own sleep cycles and use a fraction wheel to examine their data.

This activity is from The Science of Sleep and Daily Rhythms Teacher's Guide, and was designed for students in grades 6–8. Lessons from the guide may be used with other grade levels as deemed appropriate.

Teacher
Background
Objectives and Standards
Materials and
Setup
Procedure and
Extensions
Handouts and
Downloads

Teacher Background

All mammals—including humans and most vertebrates—sleep. In fact, we spend about one-third of our lives sleeping, but many aspects of sleep still are not understood. Once viewed as a passive shutting-down of most body systems, sleep now is believed to have important functions related to the processing of information by the brain, and the repair and maintenance of body systems. In humans, sleep is known to consist of several stages, each characterized by different levels of brain and muscle activity.

Many people vary their sleep patterns using external alarm clocks to meet school or work schedules. Without an alarm, most individuals sleep about the same number of hours and wake at about the same time each day. This occurs because humans’ natural daily wake-up times are governed by an internal “clock,” consisting of about 10,000 nerve cells deep inside the brain.

Even without any light or sound cues, most people sleep and wake in roughly 24-hour cycles. And while sleep patterns are stable (they change little, or very slowly), scientists have found that the amount of sleep required to be alert differs considerably from one individual to another. These differences are believed to be inherited as genetic traits.

Sleep patterns also vary by age. For instance, newborns sleep 16–18 hours each day, including several naps. At age one, children average 12–14 hours of sleep daily, including two naps. Twelve-year-olds generally sleep nine or ten hours each day, without naps. Adults sleep six to eight hours per day. The urge to nap in the afternoon is normal for all teenagers and adults, but most people override this urge by remaining active.

Sleep deprived individuals perform less effectively, remember less information, and think less clearly than those who are well rested. In some professions (truck driver, police officer, etc.), sleep deprivation can contribute to accidents. Regardless of the job, a good night’s sleep is key to performing at one’s best.

Objectives and Standards

Life Science

Behavior is one kind of response an organism can make to an internal or external stimulus.
Behavioral response is a set of actions determined in part by heredity and in part from experience.

Science, Health and Math Skills

Observing
Collecting data
Graphing
Drawing conclusions
Learning to identify and practice healthy behaviors

Materials and Setup

Materials per Student

Sheet of heavy white paper
Sheet of lightly-colored, heavy paper
Drawing compass
Protractor
Markers (different colors)
Pair of scissors
Pen or pencil
Log or journal
Copy of student sheet (see Lesson pdf)

Setup

Begin the activity with a class discussion.
Have students collect sleep data on themselves and possibly their family members.
Next, working in groups of four, they will examine their data and share results.

Procedure and Extensions

Time: 30 minutes to conduct initial class discussion; 3–7 days for students to collect sleep data; 30 minutes to discuss results.

Part 1: Sleep Observations

Challenge the class to think about all the different things they do during a typical 24-hour period. Let each student suggest one or more activities and create a list on the board.
Now ask, What activities could you leave off this list without affecting your health or how you feel? What activities must stay on the list? Why do you think so?
Explain to students that they will be examining an essential activity on the list: sleep. Then, encourage them to share what they know about sleep. Ask, When do you usually sleep? How long do you sleep? What makes you wake up? Tell students that they will be investigating their own sleep patterns to answer the question, “Does my sleep follow a regular pattern?”
Have each student create a journal, or “Sleep Log,” to record the times that he or she goes to sleep and wakes up each day, for a period of seven days. The Sleep Log should include: bedtime; how the student felt at bedtime; waking time; how the student felt when waking; whether the student used an alarm to wake up; and how the student felt during the day (tired, well rested, etc.). If possible, time the activity so that students are able to compare weeknight and weekend sleep patterns. Students may want to ask other members of their families to participate, and to record those family members’ sleep data as well.

Part 2: Looking at Data

After students have completed seven days of observations, have them plot their data on the “Sleeping Patterns Graph,” and calculate their average number of hours of sleep per night.
Have students share and compare their graphs and journals with other members of their groups. Help them to identify similarities, differences, and patterns in their graphs. Ask questions like, Do most people go to bed and wake up at about the same time each day? Did you feel particularly sleepy on any day? If so, why do you think that is? Do you see anything different about the part of the graph corresponding to that day? Did you notice a difference between days you used an alarm to wake up and days you slept until you woke naturally?
Ask students, What are some other ways to represent your sleep data? Mention that fractions can help us to represent and study data. In this case, fractions can be used to illustrate how much of each student’s day is spent sleeping.
Have the materials managers pick up their supplies. Show students how to make a circle with the compass. Have students make a circle with a 16-cm diameter on each piece of paper, mark the center of each circle with a dot, and then cut out the circles.
Tell students they will divide one circle into 24 equal sections. Ask, Why do you think the circle needs to be divided into 24 sections? [to represent a 24-hour day] As a class, discuss how to divide the circle (see student sheet). Have students progressively divide the circle into halves, fourths, and eighths; then use the protractor to create three equal sections of 15 degrees within each eighth. Instruct students to number the sections 1-24.
Have students draw and cut a radius line (line from the center point to the edge) on both circles.
To complete the fraction wheel, have students slip the cut line of one circle into the cut line of the other, so that the circles are joined and one circle slides around the other.
Ask students to set their fraction wheels to show the average number of hours of daylight within Earth’s light-dark cycle (12 hours), and then write the number as a fraction (12/24). Have students identify fractions equivalent to 12/24, using the segments on their fraction wheels as a guide.
Have students move their fraction wheels to the average number of hours they slept per day during the previous week.
Remind students that fractions are only one way to represent the parts of a whole, and that fractions also can be written as a decimal or percentage. For example, the entire circle on the fraction wheel represents one day, or 24 hours, and can be written as 24/24, or 1.0 (since 24 divided by 24 is 1.0). Because 24 hours represent the entire circle, they also represent 100% of the hours in a day.
Conclude the activity with a class discussion of the guiding question, “Does each person’s sleep follow a regular pattern?” Or, have students answer this question with a short essay in their journals. Have them include evidence to support their answers.

Extensions

If students need additional practice converting fractions to decimals and percentages, have them complete an equivalency chart by writing each hour of the 24-hour cycle. For example: Hour (23), fraction (23/24), decimal (0.958), percent (96.8%).
Have students track other essential activities in their journals, such as eating or exercising.
Have students investigate the sleeping habits of different kinds of animals: Where do they sleep, and for how long? Do they sleep at night or during the day?
Discuss how students’ sleep patterns change when they do not have to go to school (for example, during summer). Do students stay up later? Do they wake at the same time every day? Do they sleep according to a regular schedule?
Have students discuss the following questions in their groups. If an astronaut is orbiting Earth, how many times must he or she circle our planet to get the same amount of sleep that you get each night? If the astronaut slept the same percentage of time per day as you do, how much sleep, in minutes, would he or she get per 90 minutes? If the night/day cycle on Mars lasts about 25 hours, how many hours per day would you sleep if you lived on a space station there?