Sleep and Circadian Rhythms Questions
1. During this stage of sleep, brain activity measured by an EEG is most similar to the activity observed when someone is awake:
- A. stage 1
- B. stage 2
- C. stage 3
- D. REM sleep
Show Answer
Correct answer: D
Rapid eye movement, or REM, sleep is sometimes called paradoxical sleep because the brain activity observed during REM resembles what is seen when someone is awake. During REM sleep, the muscles are completely relaxed and limp but the eyes are moving rapidly. This is also the time of sleep when our most vivid dreams are likely to occur.
2. Cells in this nucleus can be considered the main "timekeepers" of the brain, as they generate and maintain rhythmic activity on a 24-hour cycle to help regulate our circadian rhythms:
- A. nucleus accumbens
- B. subthalamic nucleus
- C. suprachiasmatic nucleus
- D. red nucleus
Show Answer
Correct answer: C
The suprachiasmatic nucleus is a nucleus in the hypothalamus that contains cells that act as the circadian pacemaker of mammals. The cells "keep time" through a process of gene transcription, protein production, and protein degradation that takes approximately 24 hours to complete.
3. This stage of sleep is sometimes also referred to as "deep sleep" or "slow-wave sleep."
- A. stage 1
- B. stage 2
- C. stage 3
- D. REM sleep
Show Answer
Correct answer: C
Stage 3 sleep is also known as deep sleep or slow-wave sleep. In stage 3 sleep, brain activity (as measured by an EEG) is made up of at least 20% delta waves, which are low-frequency (slow), high amplitude waves. Stage 3 sleep is the deepest stage of non rapid-eye movement sleep, and is thought to be especially important to overall restfulness.
4. This stage of sleep is characterized by distinct EEG patterns called sleep spindles and K complexes:
- A. stage 1
- B. stage 2
- C. stage 3
- D. REM sleep
Show Answer
Correct answer: B
Stage 2 sleep is characterized by the presence of phenomena on an EEG known as sleep spindles and K complexes. Sleep spindles are trains of high-frequency waves. A K complex involves a biphasic wave that stands out from the rest of the EEG. The roles of these unique brainwave patterns is not completely clear.
5. During which stage of sleep are most voluntary muscles paralyzed, preventing movement?
- A. stage 1
- B. stage 2
- C. stage 3
- D. REM sleep
Show Answer
Correct answer: D
During REM (rapid eye movement) sleep, the brain sends signals that actively inhibit motor neurons, causing a temporary paralysis of most voluntary muscles. This muscle atonia prevents us from physically acting out our dreams, which are most vivid and frequent during REM.
6. True or False: Lucid dreaming is a scientifically verified phenomenon that can occur during sleep.
- A. True
- B. False
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Correct answer: A
Researchers have confirmed the occurrence of lucid dreaming through various methods. One approach involves instructing individuals to make specific eye movements upon entering a lucid dreaming state. Using this method, scientists have observed lucid dreamers making the specific eye movements as instructed, even though their brain activity indicated they were asleep.
7. During which stage of sleep do we usually experience our most vivid dreams?
- A. stage 1
- B. stage 2
- C. stage 3
- D. REM sleep
Show Answer
Correct answer: D
Most vivid dreaming occurs during REM (Rapid Eye Movement) sleep, a stage characterized by heightened brain activity, muscle atonia, and rapid eye movements.
8. Type 1 narcolepsy is a sleep disorder characterized by excessive daytime sleepiness and sudden muscle weakness (cataplexy). It is most directly associated with a deficiency of which of the following neurochemicals?
- A. dopamine
- B. serotonin
- C. acetylcholine
- D. orexin (hypocretin)
Show Answer
Correct answer: D
Narcolepsy is a chronic condition that causes excessive daytime sleepiness and leads to an increased tendency to fall asleep during daytime activities. Narcolepsy type 1 is linked to a loss of orexin-producing neurons in the hypothalamus, leading to low orexin levels. Orexin neurons have an excitatory effect on several regions of the brain that are involved in promoting wakefulness and suppressing REM sleep.
9. Which substance is produced as a byproduct of ATP usage and accumulates in the brain during waking states, contributing to feelings of tiredness over time?
- A. acetylcholine
- B. dopamine
- C. serotonin
- D. adenosine
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Correct answer: D
As neurons use ATP for energy, adenosine accumulates in the brain. Adenosine inhibits wake-promoting neurons and contributes to the feeling of tiredness. During sleep, adenosine levels fall, restoring alertness.
10. The suprachiasmatic nucleus (SCN) uses information from which pathway to reset the circadian clock in response to light?
- A. retinotectal pathway
- B. retinogeniculostriate pathway
- C. retinohypothalamic pathway
- D. nigrostriatal pathway
Show Answer
Correct answer: C
Specialized photosensitive retinal ganglion cells send light information directly to the SCN through the retinohypothalamic tract. This input helps synchronize the body’s internal clock with the external light–dark cycle.
11. The glymphatic system plays an important role in clearing metabolic waste from the brain. How is cerebrospinal fluid (CSF) flow through the glymphatic system thought to change during sleep compared to wakefulness?
- A. it increases during sleep
- B. it remains unchanged during sleep
- C. it decreases during sleep
- D. it stops completely during sleep
Show Answer
Correct answer: A
Evidence suggests that the glymphatic system becomes more active during sleep, allowing cerebrospinal fluid (CSF) to flow more freely through perivascular channels. This enhanced flow facilitates the clearance of metabolic waste products, such as amyloid-beta and tau, from the brain.
12. Sleep paralysis is a state of immobility that occurs just before falling asleep or upon awakening. It is thought to result from an overlap between wakefulness and which sleep stage?
- A. non-REM stage 1
- B. non-REM stage 2
- C. non-REM stage 3
- D. REM sleep
Show Answer
Correct answer: D
Sleep paralysis is generally believed to occur due to an overlap between REM sleep and wakefulness. During REM sleep, neurons in the brainstem inhibit spinal cord neurons, causing a widespread loss of muscle movement. Sleep paralysis appears to result from this REM-related paralysis persisting into wakefulness.
13. Sleepwalking most commonly occurs during which stage of sleep?
- A. stage 1 (non-REM)
- B. stage 2 (non-REM)
- C. stage 3 (non-REM)
- D. REM sleep
Show Answer
Correct answer: C
Sleepwalking typically occurs during stage 3 non-rem sleep (also known as slow-wave sleep or deep sleep). It can also occur in stage 2, but this is much less common.
14. Which of the following best describes the main role of pons signaling in REM sleep?
- A. it activates the cortex and inhibits motor neurons to cause muscle paralysis
- B. it suppresses dreaming by inhibiting cortical activity
- C. it maintains wakefulness by stimulating the reticular activating system
- D. it prevents REM sleep by increasing activity in the locus coeruleus
Show Answer
Correct answer: A
During REM sleep, certain neurons in the pons drive activation of the cortex, while others project to the medulla and spinal cord to inhibit motor neurons and cause the paralysis characteristic of REM sleep.
15. Where does the pineal gland get its name?
- A. it was first discovered by a scientist with the last name Pineal
- B. it resembles a pine cone in shape
- C. it is located near the pineal nerve
- D. it releases pinealocytes, which are shaped like pine needles
Show Answer
Correct answer: B
The pineal gland is named for its pine cone-like shape.
16. This stage of sleep is often called "slow-wave sleep" because a significant portion of brain activity during it involves low-frequency, high-amplitude waves (as measured by an EEG):
- A. non-REM stage 1
- B. non-REM stage 2
- C. non-REM stage 3
- D. REM sleep
Show Answer
Correct answer: C
Non-REM stage 3 sleep is also known as slow-wave sleep or deep sleep. In stage 3, delta waves, which are low-frequency, high amplitude waves, make up at least 20% of brain activity.
17. In the mammalian suprachiasmatic nucleus, the proteins CLOCK and BMAL1 bind together and promote the expression of which two genes central to the circadian negative-feedback loop?
- A. Per and Cry
- B. Tim and Dbt
- C. Clock and Bmal1
- D. Rev-erb and Ror
Show Answer
Correct answer: A
CLOCK and BMAL1 work together to turn on the Per and Cry genes. As PER and CRY proteins build up, they feed back and shut down CLOCK–BMAL1 activity, creating the daily on–off cycle that drives circadian rhythms in the suprachiasmatic nucleus.
18. Which region of the hypothalamus contains neurons that project to wake-promoting areas of the brain and release inhibitory neurotransmitters (e.g., GABA, galanin) to promote sleep?
- A. lateral hypothalamus
- B. tuberomammillary nucleus
- C. ventrolateral preoptic area (VLPO)
- D. mammillary bodies
Show Answer
Correct answer: C
The transition to sleep is thought to be controlled to a large degree by the inhibition of ascending arousal systems. For example, neurons in a nucleus of the hypothalamus called the ventrolateral preoptic nucleus, or VLPO, project to most parts of the ascending arousal system and release the inhibitory neurotransmitters GABA and galanin onto those wake-promoting regions.
19. Type 1 narcolepsy is most strongly associated with which pattern of orexin (hypocretin) levels?
- A. high orexin levels
- B. low orexin levels
- C. normal orexin levels
Show Answer
Correct answer: B
Narcolepsy type 1 is linked to a loss of orexin-producing neurons in the hypothalamus, leading to low orexin levels. Orexin neurons have an excitatory effect on several regions of the brain that are involved in promoting wakefulness and suppressing REM sleep. Thus, the loss of these neurons leads to deficiencies in maintaining wakefulness and is linked to the dysregulation of REM sleep.
20. Which stage of sleep is characterized by the presence of EEG phenomena known as sleep spindles and K-complexes?
- A. stage 1
- B. stage 2
- C. stage 3
- D. REM sleep
Show Answer
Correct answer: B
Stage 2 sleep is characterized by the presence of phenomena on an EEG known as sleep spindles and K complexes. Sleep spindles are trains of high-frequency waves. A K complex involves a biphasic wave that stands out from the rest of the EEG.
21. Zolpidem, commonly known by the brand name Ambien, is a drug that promotes sleep primarily by increasing activity at these neurotransmitter receptors:
- A. serotonin
- B. dopamine
- C. glutamate
- D. GABA
Show Answer
Correct answer: D
Zolpidem exerts its effects by increasing activity at receptors for the neurotransmitter GABA. GABA is primarily an inhibitory neurotransmitter, and increasing GABA activity can promote sleep as GABA can decrease activity in parts of the brain that promote wakefulness.
22. The secretory cells in the pineal gland that produce melatonin are called:
- A. chromaffin cells
- B. pinealocytes
- C. astrocytes
- D. beta cells
Show Answer
Correct answer: B
The pineal gland is made up of secretory cells called pinealocytes, which secrete melatonin throughout the 24-hour cycle. Secretion is highest in the middle of the night. It begins to decrease as it gets closer to dawn and is lowest during daylight hours.
23. True or False: Studies generally find that melatonin supplementation is effective in reducing the amount of time it takes to fall asleep.
- A. True
- B. False
Show Answer
Correct answer: A
Evidence on the effectiveness of melatonin supplementation is mixed but generally indicates that it produces modest benefits in promoting sleep. Meta-analyses suggest that melatonin can reduce the time it takes to fall asleep, slightly increase total sleep time, and improve sleep quality. It appears to be particularly effective for circadian rhythm disruptions, such as jet lag.
24. During which sleep stage do our most vivid dreams typically occur?
- A. stage 1
- B. stage 2
- C. stage 3
- D. REM sleep
Show Answer
Correct answer: D
In REM sleep, EEG activity resembles what’s seen in stage 1 or restful waking. During REM sleep, the muscles are completely relaxed and limp but the eyes are moving rapidly. This is the time of sleep when our most vivid dreams are likely to occur.
25. During REM sleep, neurons in which of the following brain regions project to the medulla and spinal cord to produce the muscle paralysis characteristic of REM sleep?
- A. cerebellum
- B. thalamus
- C. pons
- D. basal ganglia
Show Answer
Correct answer: C
During REM sleep, certain neurons in the pons drive activation of the cortex, while others project to the medulla and spinal cord to inhibit motor neurons and cause the paralysis characteristic of REM sleep.
26. Which of the following is true about the molecular clock in neurons of the suprachiasmatic nucleus (SCN)?
- A. PER and CRY proteins inhibit the activity of CLOCK and BMAL1
- B. CLOCK and BMAL1 inhibit transcription of the PER and CRY genes
- C. PER and CRY proteins activate their own gene transcription
- D. SCN rhythms are generated by melatonin released within the SCN
Show Answer
Correct answer: A
CLOCK and BMAL1 stimulate production of PER and CRY proteins. As PER and CRY accumulate, they inhibit the activity of CLOCK and BMAL1, reducing their own production. This negative feedback loop helps generate the brain's approximately 24-hour circadian rhythm.
27. Current evidence suggests that sleepwalking may occur because:
- A. the entire brain abruptly transitions from sleep to wakefulness
- B. REM sleep intrudes into slow-wave sleep
- C. wake- and sleep-like activity occur in different brain regions at the same time
- D. there is complete activation of the prefrontal cortex during slow-wave sleep
Show Answer
Correct answer: C
Although the exact cause of sleepwalking remains uncertain, evidence suggests it may result from some brain regions, such as those involved in movement, showing wake-like activity while other regions involved in conscious awareness and complex cognition remain in a sleep-like state.
