National Sleep Foundation

Chapter 1: Normal Sleep

The Physiology of Sleep – The Respiratory System

Sleep has a large impact on the respiratory system, and vice versa. Ventilation (entry and exit of air into the lungs) and respiration (transportation of oxygen into circulation in the lungs, and of carbon dioxide in the opposite direction) both change while a person sleeps. Specifically, they become faster and more erratic during rapid eye movement (REM) sleep. The cough reflex is also suppressed during REM and NREM sleep.1

In people with sleep-disordered breathing, respiration pauses often occur during sleep due to the airways either completely or partially collapsing. Obstructive sleep apnea (OSA, in which no ventilation occurs) and hypopneas (reduced ventilation due to partial airway obstruction) lead to intermittent and abrupt reduction in blood oxygen levels. These bring individuals to a more awake stage of sleep and can wake them up. Sleep-disordered breathing symptoms include snorting, snoring, gasping, and choking in one’s sleep (often these occur without the sleeper’s awareness). They result in excessive daytime sleepiness (or “tiredness”); often, the individual has no idea whey they are so tired.

This respiratory system interruption also has other, negative, long-term results, including increased activation of the adrenalin-secreting sympathetic nervous system, inflammation, and hormonal changes. These, in turn, can increase the risk of hypertension, coronary artery disease (blocked heart arteries and heart attacks), abnormal heart rhythms (like atrial fibrillation), stroke, a rise in blood sugars (glucose intolerance) to the point of diabetes, obesity, mood problems (such as depression, memory problems), and other issues. In fact, OSA significantly increased the risk of death from any cause — independent of other variables.2

References

  1. Institute of Medicine (IOM) Committee on Sleep Medicine and Research, Colten HR and Altevogt BM (ed.), Sleep Disorders and Sleep Deprivation: An Unmet Public Health Problem, Washington, DC: National Academy of Sciences, 2006.
  2. Institute of Medicine (IOM) Committee on Sleep Medicine and Research, Colten HR and Altevogt BM (ed.), Sleep Disorders and Sleep Deprivation: An Unmet Public Health Problem, Washington, DC: National Academy of Sciences, 2006.