Sleep and related disorders

Question 1

Define EOG, EMG and EEG

Answer 1

EOG: Electro-oculography
EMG: Electromyography
EEG: Electroencephalography

Question 2

What are the normal sleep stages?

Answer 2

N1, N2, N3 and REM

Question 3

What is a micro-arousal? How does it appear on EEG and EMG?

Answer 3

A transient disruption of sleep
(revealed by sudden increase in frequency and chin activity)

Question 4

Name characteristic EEG features of wakefulness, N1, N2, N3 and REM

Answer 4

Wakefulness: alpha waves (high freq, low amplitude)
N1: low amplitude, mixed freq
N2: K-complex and sleep spindles
N3: delta waves (low freq, high amplitude)
REM: low amplitude, mixed freq, loss of muscle activity, rapid eye movement

Question 5

How can we differentiate between well-consolidated sleep and poor quality sleep?

Answer 5

Well-consolidated sleep: More deep sleep (more REM stages), fewer wakefulness periods

Poor quality sleep: More lighter sleep (N1, N2, reduced REM) and more periods of wakefulness

Question 6

Where is the respiratory control system located in the brain?

Answer 6

In the medulla and pons of the brainstem

Specifically, the pre-Botzinger complex is a cluster of nerves responsible for generating the rhythmic breathing pattern of respiration

Question 7

What brain structure is responsible for wakefulness?

Answer 7

Hypothalamus

Question 8

What is the role of the lateral hypothalamic nucleus?

Answer 8

Plays a key role in regulating arousal

Question 9

The respiratory controller receives inputs from… (2)

Answer 9

• the sleep-promoting system
• the wake-promoting system

Question 9

What is the VLPO and what is its function

Answer 9

• Ventro-lateral pre-optic area
• Very important sleep-promoting area: inhibits the wake-promoting system based on signals from the circadian clock.

Question 10

During sleep, we lose…

Answer 10

the wakefulness drive to breathe.

Question 11

Loss of the wakefulness drive to breather results in…

Answer 11

• Reduced output from the controller (pre-Botzinger complex)
• Reduced muscle activity (inhibition during REM sleep)

Question 12

During REM sleep, what happens to our skeletal muscles?

Answer 12

They are actively inhibited

Question 13

Why do we have reductions in FRC during sleep?

Answer 13

Due to reduced muscle activity during sleep

Question 14

Name the normal changes in respiratory control during sleep (7)

Answer 14

1. Loss of the “wakefulness drive to breathe”
2. Reduced drive output from control
3. Reduced muscle activity (inhibition during REM)
4. Reduced end-expiratory lung volume
5. Increased upper airway resistance
6. Impaired compensation for added loads
7. Reduced responses to ventilatory stimuli (hypoxia, hypercapnia, airway receptors)

Question 15

Active muscle inhibition during REM sleep affects…

Answer 15

non-diaphragmatic respiratory muscles

Question 16

During REM sleep rib cage contributions and intercostal muscle activity is decreased. How is tidal volume maintained?

Answer 16

By increased diaphragmatic activity

Question 17

How do changes in respiratory control during sleep affect minute ventilation?

Answer 17

Decreased minute ventilation, with an increase in PaCO2

Question 18

When are brief periods of breathing instability normal?

Answer 18

At the transition from wakefulness to sleep

Question 19

Normal changes in respiratory control during sleep increase our susceptibility to..

Answer 19

blood gas disturbances during sleep in pathologic conditions, esp. during REM.

Question 20

What are the 3 types of sleep-disordered breathing?

Answer 20

1. Obstructive sleep apnea
2. Central sleep apnea
3. Sleep-associated hypoventilation

Question 21

Apnea

Answer 21

Discrete period (10s) of absent airflow

Question 22

Hypopnea

Answer 22

Discrete period (10s) of reduced airflow

Question 23

Hypoventilation

Answer 23

Sustained reduction in breathing associated with hypercapni (and hypoxemia)