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Quiz: Sleep and Brain States

Test your understanding of Chapter 10. Choose the best answer, then click Show Answer to check.

Question 1

Which structure is the brain's master circadian clock?

  1. The pineal gland
  2. The hippocampus
  3. The suprachiasmatic nucleus of the hypothalamus
  4. The thalamus
Show Answer

The correct answer is C. The suprachiasmatic nucleus (SCN), which sits just above the optic chiasm in the hypothalamus, is the master clock. The pineal gland is a common wrong answer because it releases melatonin, but it takes its timing orders from the SCN rather than keeping time itself.

Concept Tested: Suprachiasmatic Nucleus Bloom's Level: Remember

Question 2

Which EEG features are the signature of stage N2 sleep?

  1. Sleep spindles and K-complexes
  2. Alpha waves over the back of the head
  3. Sawtooth waves and rapid eye movements
  4. Tall delta waves filling most of the recording
Show Answer

The correct answer is A. N2 is marked by sleep spindles (short bursts of roughly 12 to 14 Hz waves) and K-complexes (single large waves). Tall delta waves are tempting because N2 is "real" sleep, but they define the deeper stage, N3.

Concept Tested: NREM Sleep Bloom's Level: Remember

Question 3

How much sleep does the American Academy of Sleep Medicine recommend for teenagers ages 13 to 18?

  1. 6 to 7 hours per night
  2. 7 or more hours, the same as adults
  3. 10 to 12 hours per night
  4. 8 to 10 hours per 24 hours
Show Answer

The correct answer is D. The AASM recommends 8 to 10 hours per 24 hours for teens, and the CDC uses the same range. "7 or more hours" is the recommendation for adults 18 and older, not for teens.

Concept Tested: Teen Sleep Needs Bloom's Level: Remember

Question 4

Why does an EEG during deep N3 sleep show taller waves than an EEG during alert waking?

  1. Neurons fire much stronger action potentials during deep sleep.
  2. Large groups of cortical neurons fire together in a slow rhythm, so their signals add up.
  3. The electrodes are pressed closer to the scalp when a person lies down.
  4. Fewer neurons are active, so the remaining ones are easier to record.
Show Answer

The correct answer is B. Tall, slow waves appear when many neurons are synchronized, so their electrical signals add together instead of canceling out. Option A is a common mix-up: individual action potentials are all-or-none and don't get "bigger" in sleep; it's the synchrony that changes.

Concept Tested: Brain Waves Bloom's Level: Understand

Question 5

What is the main job of melatonin in the sleep-wake cycle?

  1. It is a nighttime hormone from the pineal gland that signals darkness and helps you feel sleepy.
  2. It builds up in the brain the longer you stay awake and is blocked by caffeine.
  3. It is made by neurons in the lateral hypothalamus and keeps you awake during the day.
  4. It is released in bright morning light to wake you up.
Show Answer

The correct answer is A. Melatonin rises at night, is lowered by bright light, and helps you feel sleepy as it gets dark. Option B describes adenosine (sleep pressure), and option C describes orexin, which promotes wakefulness.

Concept Tested: Melatonin Bloom's Level: Understand

Question 6

Which statement best describes how REM sleep is distributed across a normal night?

  1. REM happens once, right after falling asleep.
  2. REM periods are about the same length all night.
  3. REM periods start short and get longer toward morning.
  4. REM is concentrated in the first half of the night, along with deep sleep.
Show Answer

The correct answer is C. The first REM period begins about 90 minutes after sleep onset and is short, and later REM periods can last about an hour. Option D is a common mix-up: it's N3, not REM, that is packed into the first half of the night.

Concept Tested: REM Sleep Bloom's Level: Understand

Question 7

Maya usually sleeps 9 hours, but during exam week her alarm cuts her nights to 6 hours. Based on a typical hypnogram, which stage will she lose the most of, as a share of its usual total?

  1. N3 deep sleep
  2. REM sleep
  3. N1 sleep
  4. All stages equally
Show Answer

The correct answer is B. Cutting the night short removes the last hours, which hold the longest REM periods, so about half of REM can be lost. N3 is the tempting answer because people think of it as "the important sleep," but it is concentrated early in the night and mostly survives a 6-hour night.

Concept Tested: Sleep Stages Bloom's Level: Apply

Question 8

A student says, "I've slept 6 hours a night for two weeks, and I feel totally used to it, so my brain must be fine." Based on the 14-day sleep-restriction study described in the chapter, what is the best response?

  1. You're right. After about a week, the brain fully adapts to 6 hours.
  2. Feeling fine means your performance is fine, because sleepiness is the best measure of impairment.
  3. Only people sleeping 4 hours or less showed any decline.
  4. People on 6 hours kept getting worse at attention tests while rating themselves only slightly sleepier.
Show Answer

The correct answer is D. In that study, people limited to 6 hours or less showed steadily growing deficits, eventually similar to up to two nights without sleep, yet their sleepiness ratings barely changed. Option C is wrong because the 6-hour group also declined.

Concept Tested: Sleep Deprivation Bloom's Level: Apply

Question 9

A 17-year-old falls asleep in class despite sleeping 9 hours, and her knees buckle when she laughs, though she stays fully aware. On an MSLT she falls asleep within minutes and enters REM in several naps. Which explanation best fits?

  1. Chronic insufficient sleep from staying up late
  2. Seizures starting in the temporal lobe
  3. Loss of orexin neurons, letting REM features intrude into waking
  4. Overproduction of melatonin by the pineal gland
Show Answer

The correct answer is C. Sleepiness despite enough sleep plus emotion-triggered weakness with preserved awareness (cataplexy) points to narcolepsy type 1, caused by loss of orexin neurons in the lateral hypothalamus. Option A is the main distractor, but insufficient sleep doesn't cause cataplexy, and she is already sleeping 9 hours.

Concept Tested: Narcolepsy Bloom's Level: Analyze

Question 10

Researchers found that Doberman pinschers with inherited narcolepsy carry a mutation in the gene for orexin receptor 2, and that people with narcolepsy have lost most of their orexin neurons. What do these two findings together suggest?

  1. Narcolepsy in people is caused by the same receptor mutation found in the dogs.
  2. Orexin signaling is needed to keep the sleep-wake switch stable, whether the problem is the signal or its receptor.
  3. Orexin is mainly a feeding hormone with no real role in sleep.
  4. Narcolepsy is caused by too much orexin activity in the brain.
Show Answer

The correct answer is B. Breaking the system at the receptor (dogs) or at the source of the signal (human orexin neurons) produces the same disorder, which shows that orexin signaling stabilizes wakefulness. Option A is tempting, but most human cases involve loss of orexin neurons, not receptor mutations.

Concept Tested: Orexin (Hypocretin) Bloom's Level: Analyze