Type I polysomnography is a sleep study performed overnight with the patient continuously monitored by a credentialed technologist.

Polysomnography no longer includes NPT monitoring for erectile dysfunction, as it is reported that all male patients will experience erections during phasic REM sleep, regardless of dream content.

However, at times nurses and respiratory therapists perform polysomnography without specific knowledge and training in the field.

It may also record other information crucial for diagnostics that are not directly linked with sleep, such as movements, respiration, and cardiovascular parameters.

In any case, through polysomnographic evaluation, other information (such as body temperature or esophageal pH) can be obtained according to the patient's or the study's needs.

The use of polysomnography as a screening test for persons with excessive daytime sleepiness as their sole presenting complaint is controversial.

This movement is equated to effort and produces a low-frequency sinusoidal waveform as the patient inhales and exhales.

The exploring electrodes are usually attached to the scalp near the frontal, central (top) and occipital (back) portions of the brain via a paste that will conduct electrical signals originating from the neurons of the cortex.

A person becomes partially paralyzed to make acting out of dreams impossible, although people that do not have this paralysis can develop REM behavior disorder.

Pulse oximetry determines changes in blood oxygen levels that often occur with sleep apnea and other respiratory problems.

For the standard test, the patient comes to a sleep lab in the early evening and over the next 1–2 hours is introduced to the setting and "wired up" so that multiple channels of data can be recorded when they fall asleep.

[citation needed] During the study, the technician observes sleep activity by looking at the video monitor and the computer screen that displays all the data second by second.

Most recently, health care providers may prescribe home studies to enhance patient comfort and reduce expense.

For example, series of drastic blood oxygen desaturations during night periods may indicate some form of respiratory event (apnea).

More sophisticated home study devices have most of the monitoring capability of their counterparts run by sleep lab technicians, and can be complex and time-consuming to set up for self-monitoring.

[citation needed] After the test is completed, a "scorer" analyzes the data by reviewing the study in 30-second "epochs".

Ideally, interpretation is done in conjunction with the medical history, a complete list of drugs the patient is taking, and any other relevant information that might impact the study such as napping done before the test.

After interpreting the data, the sleep physician writes a report that is sent to the referring provider, usually with specific recommendations based on the test results.

The below example report describes a patient's situation and the results of some tests, and mentions CPAP as a treatment for obstructive sleep apnea.

CPAP is typically prescribed after the diagnosis of OSA is made from a sleep study (i.e., after a PSG test).

To determine the correct amount of pressure and the right mask type and size, and also to make sure the patient can tolerate this therapy, a "CPAP titration study" is recommended.

In summary, this split night study shows severe OSA in the pre-CPAP period, with definite improvement on high levels of CPAP.

Based on this split night study I recommend he start on nasal CPAP 17 cm H2O along with heated humidity.