Day Testing: Sleep Disorders And Diagnosis

Sleep disorders can be diagnosed through a variety of tests, including sleep studies, which are formally known as polysomnograms (PSG). Sleep studies are diagnostic tests that track and record the activity of multiple body systems, including the heart, brain, and respiratory system, to provide healthcare providers with a comprehensive view of the quality of an individual's sleep. These tests are typically conducted overnight at a sleep centre, which may be a designated room in a hospital, a sleep laboratory, or a specially equipped hotel room. However, for those who work night shifts, daytime sleep studies can be scheduled if necessary.

Polysomnography (PSG)

PSG involves the use of several sensors that track the activity of multiple body systems, including the heart, brain, and respiratory system. These sensors include electroencephalography (EEG), which detects brain waves; electrocardiography (EKG or ECG), which measures the electrical activity of the heart; electromyography (EMG), which monitors muscle movement; and electro-oculography (EOG), which is used to detect eye activity.

During a PSG, sensors are attached to the patient's head, chest, face, and leg. The patient is then asked to perform simple tasks, such as moving their eyes and legs, to ensure that the sensors are working correctly. The patient then relaxes and falls asleep, during which their sleep activity is monitored. PSG can be performed overnight or during the day for those who work night shifts.

PSG data can provide valuable information such as sleep onset latency, REM-sleep onset latency, the number of awakenings during sleep, total sleep duration, and percentages and durations of each sleep stage. It can also record other crucial parameters, such as movements, respiration, and cardiovascular data.

While PSG is a common and effective diagnostic tool, it is not without its limitations. Some people may experience mild discomfort or irritation from the adhesives used to attach the sensors. Additionally, the unfamiliar environment and presence of sensors may affect the patient's sleep quality and duration.

At-home sleep apnea tests

A sleep study, formally known as a polysomnogram, is a diagnostic test that tracks and records the activity of multiple body systems, including the heart, brain and respiratory system, to provide healthcare providers with a comprehensive view of the quality of an individual's sleep. Sleep studies are typically performed overnight, but can also be scheduled during the day for people who work night shifts and sleep during the day.

An at-home sleep apnea test is a simplified breathing monitor that tracks your breathing, oxygen levels and breathing effort. It is a cost-effective alternative to an overnight sleep study, which provides a more thorough assessment of sleep issues. At-home sleep apnea tests are best suited for people who are suspected of having moderate to severe obstructive sleep apnea that isn’t complicated by other disorders.

• Talk to your doctor about your symptoms, personal health history and family history.
• Get a prescription from your doctor for an at-home sleep apnea test.
• Get your test delivered to your home or pick it up from a sleep centre.
• When you're ready to use the test, follow the instructions to place the sensors on your body correctly. The sensors include a small probe over your finger that measures oxygen levels, a mask with tubes that you insert into your nostrils, and additional sensors placed on your abdomen and chest to measure their rise and fall as you breathe.
• Turn on the device and try to sleep as you normally would with the sensors attached to your body. Most studies require one full night of sleep, including at least four hours of uninterrupted monitoring data.
• When you wake up, turn off the device and remove the sensors.
• Return the device if required.
• Discuss the results with your doctor, who may recommend additional tests or treatment options.

Overnight oximetry

The test typically involves attaching a plastic clip, called an oximeter, to the end of the patient's finger. This clip is painless and can be easily removed. It is usually connected to a small box that records data overnight. Newer devices may adhere directly to the skin and provide similar measurements.

Within the overnight oximeter sensor is a red light that shines through the patient's finger or the surface of their skin. On the other side of the light is a sensor that measures the patient's pulse and the oxygen content of their blood. The colour of the blood, which varies depending on the amount of oxygen it contains, changes the frequency of the light wavelength that is reflected back to the sensor.

Pulse oximetry data is recorded continuously throughout the night and is then reviewed by a medical professional. They will be able to determine if there are abnormal drops in oxygen levels, called desaturations, which may be indicative of sleep apnea.

While overnight oximetry is easy and inexpensive, it is not a perfect test. Oximeters only provide a limited amount of information, and there are subtleties involved in sleep disorders that may not be detectable. For example, sleep position and sleep stages may impact the degree of oxygen changes, especially when sleeping on the back. Therefore, additional tests such as polysomnography are often required before a diagnosis can be made.

Multiple Sleep Latency Testing (MSLT)

The Multiple Sleep Latency Test (MSLT) is a full-day test that evaluates excessive daytime sleepiness and potential underlying sleep disorders. The test is conducted during daytime hours, usually the day after an overnight sleep study in a hospital or sleep centre. The MSLT measures how long it takes a person to fall asleep and what sleep stages they experience across multiple short daytime nap opportunities.

The MSLT is used to diagnose narcolepsy and hypersomnia, two sleep disorders marked by excessive daytime sleepiness and sometimes oversleeping. Excessive daytime sleepiness may also accompany insomnia, obstructive sleep apnea, periodic limb movement disorder, and circadian rhythm disorders. It is characterised by a strong urge to sleep during the daytime, which can make it difficult to stay alert and go about daily activities.

The MSLT involves a series of four or five short naps, broken up by two-hour breaks. During the test, the patient lies in a bed in a dark, quiet room, and is monitored using sensors to measure brain activity and eye movements. The patient is awakened 15 minutes after falling asleep, or after 20 minutes if they are unable to fall asleep.

To prepare for an MSLT, it is recommended to maintain a steady sleep routine in the weeks leading up to the test. This includes keeping a sleep diary or wearing an actigraph to monitor sleep-wake activity, and avoiding drugs, medications, and stimulants such as caffeine.

Actigraphy

The test is designed to interfere as little as possible with the wearer's daily life, so they can continue their normal routine while wearing the device. The data collection process usually takes place over several days or even weeks.

• The time the wearer falls asleep and wakes up
• How long it takes the wearer to fall asleep
• The total sleep time
• How much time the wearer spends awake during the night after initially falling asleep

Frequently asked questions