Our bodies perform numerous involuntary functions in order to keep us alive. The transmission of signals from the brain through the nervous system, inhaling and exhaling with our lungs to supply oxygen to the blood through our respiratory system, the beating of our hearts to keep the blood flowing to our tissues and organs through the vascular system… all of these — and many others — are essential to enable our bodies to survive and function properly. Yet, we don’t have to think about these functions. We do not need to constantly order our bodies to do these things. It is the nature of our bodies to perform these actions on “auto-pilot,” unconsciously, even while we are sleeping.

Hypopnea (pronunciation: “high-POP-knee-uh”) is a malfunction of the respiratory system. It is a condition wherein the individual breathes in a very shallow way or at an abnormally slow rate. People with hypopnea can experience an unhealthy low level of oxygen in the blood, called hypoxia.

(Generally, hypo- means low, or too little of something, as opposed to hyper-, meaning high, or too much. For example, a hypodermic needle injects medicine below the skin. A hyperactive child is thought to be subject to over-stimulation.)

With the related and more well-known breathing disorder called apnea, the patient intermittently stops breathing altogether, but with hypopnea, he suffers from periods of arrhythmic and restricted air flow. However, the two conditions are not exclusive and often occur in tandem.

Sleep DisorderLike apnea, if hypopnea occurs during sleep, it is considered a sleep disorder. (It can affect the individual while asleep or awake, but one can only experience hypopnea during waking hours due to a neuromuscular disorder.) Unfortunately, like other sleep disorders, the sufferer is often left unaware that he or she is experiencing this particular problem, yet feels unexplained negative effects during the day.

Sleep hypopnea can disrupt a healthy sleep routine not by waking us up during the night, but by leaving us feeling tired even though we’ve gotten a proper night’s rest of the typically recommended duration for our age and condition. If you are sure you’re getting a sufficient number of hours of sleep per night, but still feel fatigued during the day, sleep hypopnea is an uncommon but possible culprit you may want to discuss with your doctor.