Sleep apnea / sleep apnea syndrome (SAS), obstructive sleep apnea syndrome (OSAS) and central sleep apnea

We distinguish between obstructive and central apnea (breathing pauses). When both forms occur in a patient, it is called a mixed sleep apnea syndrome.

The sleep apnea syndrome is a common disease (similar to bronchial asthma). It affects more men than women and has a peak incidence at the age of 45-65 years.

By far the most common form is obstructive sleep apnea syndrome (OSAS). The direct cause of OSA is a relaxation of the circular muscles around the upper airway during sleep. Thus, this part of the respiratory tract (which is not like the larynx and trachea held open by cartilage) is no longer in a position to oppose the negative pressure created by inhalation. The upper part of the airways (pharynx region above the larynx) collapses partially (hypopnea) or completely (apnea) and there is an obstruction, partially to complete occlusion (obstruction) of the upper respiratory tract.

An apnea occurs when the respite lasts less than ten seconds of a hypopnea if the respiratory current is reduced by 50% and a reduction of the oxygen content is measured. Often, these respiratory arrest lead to a substantial loss of blood oxygen (hypoxia / hypoxemia), this can lead to an insufficient supply of oxygen to important organs such as brain and heart. In severe sleep apnea more than 50 breathing pauses per hour can occur. The individual breathing pauses often take longer than a minute.

To avoid death by suffocation the human brain warns the body (arousals / micro arousals) so that breathing is restored. Usually the patient does not remember such arousals. In rare cases, the person awakes with a feeling of not getting enough air. Often such arousals are then connected to a dreams about choking.

Since nearly every breathing pause will be ended by arousal, the physiological structure of sleep is destroyed. Especially the deep sleep that is important for the physical recovery of the body is reduced, in some cases deep sleep  phases are no longer detectable. Usually there is also a reduction in the proportion of REM sleep (important for the "psychic" recovery). The consequences are fatigue, daytime sleepiness, sleepiness, nodding off, aggressive behavior and often even impotence.

Recurrent breathing pauses with decreasing oxygen content in the blood result in irregular heartbeat, rise of blood pressure, less supply of the brain and the heart with an increased risk of circulatory disorders of the heart (coronary artery disease) as well as heart attack or stroke. Diabetes (diabetes mellitus) is also affected by sleep apnea.

The pure form of central apnea is much less common. It can be caused by damage in the central nervous system (vascular, cardiac arrhythmias, stroke, congenital disorders, drug use, infections of the brain) and other causes. There is a lack of control of the respiratory muscles, the respiratory center in the medulla oblongata "forgets" to give the order to breathe. Usually, the resulting reduction in blood oxygen tension is less pronounced than in patients with obstructive sleep apnea syndrome.

Obstructive sleep apnea syndrome has usually no single cause, there is often a variety of factors for this disease.

Considered as risk factors:

  • Overweight (80% of the affected are obese, but there is also people of normal weight with severe sleep apnea syndrome),
  • nasal obstruction due to polyps and / or a marked deformity of the nasal septum
  • enlarged tonsils (especially in children),
  • - constitutional relaxation of throat muscles, predisposition, heredity
  • increased alcohol consumption (especially right before bedtime), sedatives (e.g. Valium), ecstasy and other drugs
  • congenital malformations and deformities of the lower jaw (retrognathia)
  • Magnification of the soft tissues (e.g. tongue) caused by acromegaly (excessive hormone production by a usually benign tumor of the pituitary gland)


Partners of OSAS patients mostly report loud and irregular snoring. The snoring is interrupted by pauses in breathing that are terminated with a fierce, sighing breath, or heavy snoring.

Many snorers do not suffer from a sleep apnea, but unfortunately not every patient with OSAS is a snorer.

Other symptoms of obstructive sleep apnea syndrome may include:

  • maintaining sleep,
  • daytime fatigue, sleepiness at day
  • headache upon awakening ("I'm knocked out")
  • dry mouth upon awakening,
  • night sweats,
  • nocturnal urination
  • nodding off / imperative drowsiness, sometimes without warning,
  • memory disturbances, concentration problems
  • depression, depressed mood,
  • erectile dysfunction, loss of libido, impotence
  • restless sleep, difficulty staying asleep.
  • An untreated sleep apnea patient who is tired or distracted pathologically should not drive, especially with passengers. Probably, many serious traffic accidents are due an untreated sleep apnea.

Two to four weeks after beginning a regular nCPAP therapy, the ability to drive is usually fully restored. Regular follow-ups - including the acceptance of therapy - are necessary. Currently only a few occupational health services check their employees for the presence of sleep-related breathing disorders like sleep apnea. In severe cases, the nCPAP-therapy devices can also be operated in the car or truck with the on-board system.