Hypopnea is a sleep disorder that is similar to apnoea but involves periods of overly shallow breathing or an abnormally low respiratory rate whereas apnoea is where breathing stops altogether. Therefore hypopnea is less severe a condition than apnoea but can nevertheless be frightening for sufferers. It can be that you have the condition and get a full night’s sleep but don’t feel rested because you didn’t get the right kind of sleep.
There are various causes of hypopnea including:
- Physical problem such as nasal septum deformation or a congenital narrowness of the nasal meatus (nose canal) and the gullet
- Severe cases of tonsillitis and/or adenoiditis
- Being overweight
- Any neuromuscular disease or condition that means the respiratory muscles are weakened
- Using sedatives or sleeping pills
- Alcohol abuse
- The ageing process
Nasal septum deviation is where the nasal septum becomes displaced and around 80% of people that have this condition never realise it. It can occur from an impact accident or a blow to the face or it can be something that happened as a child or during childbirth. In itself, it causes difficulty in breathing and infections around the sinuses as well as hypopnea and apnoea. As well as the poor sleep, people often experience repeated sneezing, nosebleeds and pain in the face along with an impaired ability to smell.
The most common symptom of hypopnea is that people are excessively sleepy due to the lack of proper sleep. People with the condition also tend to have a loud, heavy snore that is broken up by choking sounds or loud snorts then short periods of silence when the air cannot get through to the lungs. This period can be around 20 seconds or longer and can happen as often as every hour.
Other symptoms due to the condition can be depression, mood changes, forgetfulness, loss of concentration, lack of energy and nervousness. However, these are not always found by suffers and not all people with these conditions have hypopnea.
The most direct consequence of sleep hypopnea is that the carbon dioxide in the blood increases and the oxygen levels decrease, relative to how serious the airway is obstructed. Generally, this means that people have a disrupted sleep pattern leading to fatigue, lethargy, lack of concentration, being irritable and headaches in the morning. Or in other words, they act like someone who is really tired.
There are two main types of hypopnea; central or obstructive. With obstructive hypopnea, the airway is only partial closed but it is closed enough to cause the physical effects.
There is a hypopnea index (HI) used to decide the severity of the condition whereby the number of events during a sleep period are divided by the number of hours slept. Another method to diagnose severity can be the Respiratory Disturbance Index, which is also used for sleep apnoea and other conditions, but take into account events that do not disturb sleep but may be part of the condition.
One of the main treatment for the condition is called continuous positive airway pressure (CPAP). This is where the patient wears a mask that covers their nose and/or mouth and an air blower pushes air through the upper airway. The amount of pressure used can be altered so that it maintains the oxygen levels in the blood.
Another treatment used is an oral appliance. This is the preferred method of the American Academy of Sleep Medicine especially for those with mild to moderate versions of the condition. It is also used where people cannot manage to have the mask fitted in the CPAP treatment. Oral appliances are custom made by a dentist who has been trained in dental sleep medicine.
Mild versions of the condition can be treated on some occasions by lifestyle changes such as avoiding alcohol or stopping smoking. Also, learning to avoid sleeping on your back can sometimes have a beneficial effect, as can losing weight if you are overweight. The use of sedative has been found to help some people, as have hypnotics.
Finally, surgery is a last-resort treatment and is only used when the person has a problem in the upper airway. It can involve removing an obstruction such as tonsils, adenoids or the uvula so is not a solution for everyone who suffers with the condition.