Explore how sleep works, what shapes our sleep habits, and what research can—and cannot—tell us about dreams.
Preview
Questions with solutions-
1. Chọn đáp án đúng.
Which evening habit would best support Elena's goal?
Bright evening light can delay the body's internal clock. Elena wants to start feeling sleepy earlier.
- Keep bright ceiling lights on until she falls asleep.
- Dim the room lights as bedtime approaches.
- Increase her screen brightness during her bedtime routine.
Show solution
- Dim the room lights as bedtime approaches.
Light is a timing signal for the body, not just something that helps us see.
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2. Chọn đáp án đúng.
What can someone reasonably conclude after coffee makes them feel more alert?
Caffeine blocks some of the brain's signals for sleepiness rather than replacing sleep.
- They may feel more awake while still needing sleep.
- Their need for sleep has disappeared.
- Their body has already recovered from a short night.
Show solution
- They may feel more awake while still needing sleep.
Caffeine can remain active for several hours, so having it late in the day may also make falling asleep harder.
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3. Chọn đáp án đúng.
What is one effect of this reduced muscle activity?
During rapid eye movement (REM) sleep, the brain is active, but many muscles used to move the body have greatly reduced activity.
- It prevents the brain from producing vivid dreams.
- It keeps the sleeper's eyes completely still.
- It helps limit large body movements during dreams.
Show solution
- It helps limit large body movements during dreams.
Eye movements and breathing continue even while many other muscles are less active.
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4. Chọn đáp án đúng.
How would an early sleep period typically differ from a later one?
Deep non-REM sleep tends to be more common early in the night. REM periods generally become longer toward morning.
- The early period would usually contain more deep sleep, and the later one more REM sleep.
- The early period would usually contain more REM sleep, and the later one more deep sleep.
- Both periods would contain exactly the same proportions of each sleep stage.
Show solution
- The early period would usually contain more deep sleep, and the later one more REM sleep.
Sleep cycles repeat during the night, but their balance of stages changes.
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5. Chọn đáp án đúng.
Why is falling asleep quickly not enough to show that sleep was good?
Alcohol may make a person feel sleepy at first, but it can disrupt sleep later in the night.
- The time spent falling asleep determines every aspect of sleep quality.
- Sleep quality also depends on what happens after sleep begins.
- Any substance that causes sleepiness also supports uninterrupted sleep.
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- Sleep quality also depends on what happens after sleep begins.
Brief awakenings can interrupt sleep even when the person does not remember them the next morning.
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6. Chọn đáp án đúng.
What is the most realistic expectation for Saturday?
During the week, Ben regularly sleeps less than he needs. On Saturday, he plans to get extra sleep.
- One long night will reliably reverse every effect of the week's short nights.
- His body cannot benefit from extra sleep after several short nights.
- Extra sleep may help, but it does not guarantee full recovery.
Consider the difference between helping recovery and guaranteeing complete recovery.
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- Extra sleep may help, but it does not guarantee full recovery.
Different effects of sleep loss can recover at different rates. Regularly getting enough sleep is more reliable than depending on one catch-up night.
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7. Chọn đáp án đúng.
Which response best addresses this temporary effect?
Priya wakes from a long nap feeling briefly groggy. This temporary difficulty becoming fully alert is called sleep inertia.
- Give herself time to become fully alert before starting a demanding task.
- Schedule her most demanding work for the first moments after waking.
- Assume that a longer nap will always prevent grogginess when she wakes.
Show solution
- Give herself time to become fully alert before starting a demanding task.
Sleep inertia tends to be stronger after waking from deeper sleep, so a longer nap does not always mean an easier awakening.
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8. Chọn đáp án đúng.
What does this suggest about early school mornings?
During adolescence, the body's preferred sleep schedule often shifts later. A teenager may struggle to fall asleep early even when tired.
- They prove that teenagers need less sleep than adults.
- They may conflict with teenagers' natural sleep timing.
- They automatically make teenagers feel sleepy earlier that evening.
Show solution
- They may conflict with teenagers' natural sleep timing.
A later body clock does not mean a lower need for sleep; teenagers generally need more sleep than adults.
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9. Chọn đáp án đúng.
Which conclusion is justified by Leah's report?
Leah says she almost never remembers a dream. Her friend concludes that she never dreams.
- She misses REM sleep on most nights.
- Her brain is less active during sleep than the brains of people who recall dreams.
- She recalls few dreams, but this does not show that she never dreams.
Experiencing something and remembering it are different.
Show solution
- She recalls few dreams, but this does not show that she never dreams.
Dream memories often fade quickly after waking, making recall an incomplete record of dreaming.
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10. Chọn đáp án đúng.
Why should the device's sleep-stage labels be treated as estimates?
A wrist device uses movement and heart rate to label periods of light, deep, and REM sleep.
- It infers sleep stages from indirect signals rather than directly measuring brain activity.
- Each heart rate value identifies exactly one sleep stage.
- It records brain waves directly through the wrist.
Think about what the device actually measures.
Show solution
- It infers sleep stages from indirect signals rather than directly measuring brain activity.
Laboratory sleep studies combine brain activity, eye movements, and muscle activity to identify sleep stages.
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11. Chọn đáp án đúng.
Which claim does this result support?
In a controlled study, two groups learn the same word pairs. After the same length of time, the group that slept remembers more than the group that stayed awake.
- Remembering a dream is necessary for retaining new information.
- Sleep can help people retain recently learned information.
- The content of a dream determines which information is retained.
The study measured memory performance, not dream content.
Show solution
- Sleep can help people retain recently learned information.
Better memory after sleep supports a benefit, but explaining the mechanism requires more than a difference in test scores.
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12. Chọn đáp án đúng.
Which conclusion stays within the evidence?
Researchers have proposed that dreams may relate to memory or emotional processing. There is no scientific agreement on one main purpose of dreaming.
- Every dream contains a fixed message that researchers can decode.
- Because theories differ, dreams cannot have any function.
- Dreams may relate to several mental processes, but their full function remains uncertain.
Uncertainty does not establish either a universal explanation or the absence of a function.
Show solution
- Dreams may relate to several mental processes, but their full function remains uncertain.
A possible function is a hypothesis to investigate, not a universal rule for interpreting individual dreams.