Sleep apnea is a condition characterized by cessation of breathing when the individual is asleep, often for a minute or longer, several times throughout the night. The obstructive form of this condition, known as Obstructive Sleep Apnea (OSA), results from a physical closure of the airway during the person's sleep. As the breathing stops in affected people, they wake up momentarily, reopening the airway. Although patients may be able to go back to sleep immediately, the normal sleeping pattern is interrupted multiple times, resulting in a failure to attain the deep sleeping state which necessary for relaxation. Thus, affected patients appear not rested upon awakening, have morning headaches, limited attention and concentration, personality changes, and are sluggish and tired during the day. At night, they can be noticed by family members to be heavy snorers. In most affected people, the cause of this obstruction is a relaxation of the muscles supporting the soft palate, extending to the base of the tongue, during sleep. Obesity is a major risk factor for the development of OSA. As fat deposition increases on the sides of the upper airway, the airway narrows, and tends to close completely upon normal relaxation of the supporting muscles. Loss of muscle mass with increasing age is another factor for increased risk of development of OSA. In addition, males have a higher chance of contracting the condition, probably due to the effect of male hormones in causing structural changes in the airway. Other risk factors include anatomic abnormalities, enlarged tonsils, consumption of alcohol prior to sleeping, smoking, and/or nasal congestion. It is estimated that about 2% of women and 4% of men are affected by OSA.
Most OSA patients are unaware that their sleep pattern is disturbed and are at a loss for understanding the perpetual tiredness and behavioural changes they undergo. Sleep studies, also known as polysomnography, involves measuring the brain pattern, eye movements, muscle movements, oral and nasal airflow, the size and frequency of breaths, and the loudness of snoring to make an objective evaluation of OSA. Treatment strategies may differ according to the cause of the obstruction. In most cases, reducing obesity is a major goal of the treatment. Patients may be asked to abstain from drinking alcohol or taking sedatives from going to sleep. In some cases, a special mask can be worn over the nose and mouth, providing a mechanical breathing assistance. In extreme cases, surgery to remove either the tonsils or excess tissue at the back of the mouth may be required.
Obstructive sleep apnea can run in families. Affected members in such families have been noticed to share similarities in their facial and airway structures. Although no specific genetic marker has been found to be conclusively associated with OSA, it is assumed that obesity and OSA share a number of susceptibility genes. Several studies have indicated an increased probability of OSA among individuals carrying the ApoE4 allele.