Sleep
In this section, we'll be learning about sleep and circadian rhythms.
1) Start with this video:
2) Watch this video for a review of sleep stages:
3) Now, answer these questions to test your understanding:
1. 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.
2. 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. Stage 3 sleep is thought to be especially important to overall restfulness.
3. 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.
4. 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.
5. 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
Show Answer
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.
