What is sleep disordered breathing?

Author: Sharon Jang | Reviewer: Viet Vu | Published: 10 March 2020 | Updated: ~

Illustration accompanying What is sleep disordered breathing?

Obstructive sleep apnea occurs when the throat muscles relax (highlighted by the red circle), resulting in a blockage of your airway.1

Sleep disordered breathing is an umbrella term for conditions that involve an interruption of breathing throughout the night. In research, sleep disordered breathing is evaluated by observing two key factors:

  • Apnea, a loss of air flow for 10 seconds or more, and
  • Hypopnea, a partial blockage of an airway resulting in decreased air flow to the lungs and decreased oxygen in the blood.

When you sleep, the body normally goes into a state of hypoventilation, or a slow and shallow breathing. This results in a decrease in oxygen circulating in the blood. However, weak evidence suggests that after an SCI, hypoventilation becomes more prevalent during sleep when compared to able-bodied people. Among those with SCI, hypoventilation occurs more often in individuals with tetraplegia versus paraplegia.

The two most common disorders under sleep disordered breathing include:

  • Obstructive sleep apnea, which occurs when the throat muscles relax and temporarily block your airway, and
  • Central sleep apnea, which occurs when the brain is unable to properly send signals to the breathing muscles. This occurs when your unconscious breathing stops.

Of the two types of sleep apneas, obstructive sleep apnea is more prevalent among individuals with SCI of all levels. However, central sleep apnea is more prevalent among individuals with cervical level injuries. Narcotic use can also increase the risk of central sleep apnea. It is important to note that some patients have mixed sleep apnea, a combination of obstructive and central sleep apnea.

The prevalence of sleep apnea in individuals with spinal cord injury is two to five times greater than that in the non-SCI population. In the SCI population, research has found that sleep apnea rates vary from 27-82%. The variation in prevalence can be attributed to different diagnostic measures used in research studies (e.g., evaluating sleep apnea in a lab versus home setting) and the way each study defines sleep apnea. Level of injury and type of injury also influence the prevalence of sleep apnea in the SCI population.