For Children

1.  Polysomnography: Though it is commonly used for diagnosis in children, it was not designed for the purpose. As the children's physiology and respiratory rates are high, the machine designed for adults can not be precisely used.
2.  Esophageal pressure monitors: To note the increased respiratory effort in children with upper airway resistance syndrome, esophageal pressure monitoring is essential. Polysomnography is not very useful in these conditions. A pressure probe kept in the esophagus measures frequent or extreme negative pressures that lead to disruption of their sleep.
3.  Apnea-hypopnoea index and minimum oxygen saturation levels are taken as indicators to test the average number of apneas and hypopnoeas in an hour of sleep.
4.  Video photography is used to record apnea events and night time awakening in children.
5.  Nasopharyngoscopy provides information on the degree of obstruction in the nasal passage of the child.
6.  Lateral neck radiography gives information about the size of the adenoids.
7.  Pulse oximetry, is a screening tool for obstructive sleep apnea disorder. But greater accuracy cannot be obtained.

For Adults

1.  Before going to the physician it is necessary for the person to maintain a sleep dairy about how loud the person is snoring, whether they wake up in sleep, whether they are experiencing difficult breathing (choking or gasping).
2.  Sound-activated audio recorder is another instrument, which helps in self-diagnosis.
3.  Endoscopy of nose and throat can verify blockages.
4.  X-rays or a CT scan of the head and neck can be obtained if necessary, to get a better picture.
5.  The basic diagnosis in the doctors office and includes a general examination on the pattern of sleep, the activities of the person throughout the day and medical history. This information is obtained from the patient and his family.
6.  Checking for any growth of extra tissues in mouth, nose and throat especially tonsils, uvula and soft palate.
7.  Polysomnogram: It is a painless sleep recording monitor which tests the breathing pattern in the night. It is mostly performed at sleep centers or laboratories in a hospital. It records the brain activity, eye movement, muscle activity, breathing and heart rate, amount of airflow in and out of the lungs when the body is at rest and the percentage of oxygen in the blood. After recording these details, the number of times breathing is impaired during sleep is tailed and the severity is graded.
8.  Multiple sleep latency test (MSLT): This test is performed to measure the speed at which the person falls asleep. In this test, several opportunities are given to the patient, to fall asleep during the course of a day when they are normally awake.
9.  Oximetry: In this painless method simple sleeve is inserted over one finger of the person to monitor and record oxygen levels throughout the night at home. During sleep, the oxygen level during apneas will drop down and subsequent rises with awakenings. If the results are abnormal, polysomnography is done to reconfirm the diagnosis.
10.  Electroencephalogram (EEG): This is done to monitor repeated awakenings in sleep and apnea can be diagnosed by checking brain waves of the patient.