Sleep and vigilance tests

The most common sleep study is a cardiorespiratory polygraphy used to scan for possible abnormal breathing patterns during sleep (sleep apnoea), partial upper airway obstruction and periodic leg movements during sleep.

The hospital will instruct the patient on how to attach the device used in the examination, and they will sleep normally through the night at home in their own bed. The system records their breathing and respiratory movements, heart rate, posture, leg movements, ambient sounds and blood oxygen saturation.

At Tyks Main Hospital, cardiorespiratory polygraphies are performed by the Clinical Neurophysiology Unit and the Pulmonary Diseases Outpatient Clinic. The examination is also available via the Salo, Loimaa, Vakka-Suomi and Turunmaa hospitals.

Patient instructions for cardiorespiratory polygraphy (Hoito-ohjeet.fi)

PSG is a more extensive examination than cardiorespiratory polygraphy. In addition to breathing, it records electrical activity in the cerebral cortex (EEG), making it possible to identify abnormalities in sleep structure and specific sleep disorders.

Polysomnography can be performed either with portable equipment at home or at the Tyks Clinical Neurophysiology Unit, in which case a video recording is also included.

Patient instructions for polysomnography (Hoito-ohjeet.fi)

Actigraphy studies the circadian rhythm, i.e. when the patient sleeps, when they are awake and active, and how regular their circadian rhythm is. The examination also provides information about how quiet the sleep cycles are. Actigraphy is not able to record the different stages of sleep or nocturnal breathing disorders.

An actigraph is a wristwatch-like measuring device that is used to measure movement activity over a period of several days. Typically, the test takes two weeks. The patient is allowed to lead a normal life and follow their own circadian rhythm during this period. In Tyks, actigraphy is performed by the Clinical Neurophysiology Unit.

Patient instructions for actigraphy (Hoito-ohjeet.fi)

The purposes of a multiple sleep latency test are to determine the time it takes for the patient to fall asleep and to assess the quality of their sleep.

The patient lies in bed in a dark room, trying to fall asleep. There will be four or five 20-minute registration sessions during the day (between 8 am and 5 pm), every two hours.

The test is used to study abnormal daytime fatigue and excessive sleepiness (narcolepsy and hypersomnia). In Tyks, the MSLTs are performed at the Clinical Neurophysiology Unit.

Patient instructions for a multiple sleep latency test (Hoito-ohjeet.fi)

MWT studies the patient’s ability to stay awake in monotonous situations. It can be used to determine whether the patient can be issued a driving licence or whether they can keep an existing one if they have a condition that causes daytime tiredness, such as sleep apnoea or narcolepsy.

In a maintenance of wakefulness test, the patient tries to stay awake for 40 minutes while sitting still with their eyes open in a reclining chair in a dimly lit room. There will be four sessions during the day (between 8 am and 3 pm), every two hours. In Tyks, MWTs are performed at the Clinical Neurophysiology Unit.

Patient instructions for a maintenance of wakefulness test (Hoito-ohjeet.fi)