The Cenas sleep medicine centre is equipped with the latest technologies for assessing and diagnosing all sleep and alertness disorders : sleep apnea, insomnia, hypersomnia, restless legs syndrome, sleepwalking, etc.
The Cenas Sleep Medicine Centre is equipped with the latest technologies for assessing and diagnosing all sleep and alertness disorders : sleep apnoea, insomnia, hypersomnia, restless legs syndrome, sleepwalking, etc.
What is polysomnography ?
Polysomnography is the most comprehensive test for studying sleep patterns and detecting possible sleep-related disorders.
It monitors numerous physiological parameters such as brain activity, muscles electrical activity, eye movements, breathing, cardiac activity and oxygen levels using various sensors and electrodes.
This examination takes place during a night stay at the sleep centre, and sometimes throughout the following day (especially for alertness assessments). The patient is filmed throughout the polysomnography in order to correlate the data collected with the activity observed visually and in real time by a sleep technician.
The purpose of polysomnography
Polysomnography helps assess the quality, quantity and organisation of sleep, and identify possible disorders such as sleep apnoea or periodic limb movements.
A team of specialised and experienced technicians continuously monitors the patient throughout the night. On the following day, the daytime technician team analyse and correct the data collected. The analysis is validated by a sleep specialist. They interpret the results in the context of the patient’s clinical issue. A summary of the results as well as a therapeutic proposal are then communicated to the prescribing physician.
Additional night-time examinations
Some additional tests are performed at the Sleep Medicine Centre in conjunction with the polysomnography. However, some tests can also be carried out at home. In this case, the patient equip themselves with the monitoring device following the technician’s recommendations.
Capnometry (or capnography) is a supplementary test carried out during a polysomnography. This test is performed throughout the night and measures the carbon dioxide (CO2) levels in the patient’s respiratory gases using a sensor on their forehead.
Oximetry (or saturometry) is the recording at night of oxygen levels in the blood to identify potential hypoxemia (low blood oxygen), which is symptomatic of sleep apnoea. Oximetry can be carried out at the centre as supplementary test during the polysomnography, or at home using a fingertip sensor.
With a small bracelet (actimeter) worn on the wrist, it is possible to track the patient’s sleep/wake cycles over several weeks. This allows the physician to assess possible phase shifts and estimate the amount of sleep the patient is getting.
This exam is carried out at the patient’s home, wearing the device 24 hours a day over a minimum of one week.
The respiratory polygraph looks for specific markers and oxygen levels in the patient’s blood during sleep. This exam is useful for confirming an obstructive sleep apnoea diagnosis.
Unlike polysomnography, this test is carried out at home. The patient wears two belts (one around the chest and one around the lap) to record respiratory movements, a sensor at the base of their neck to record snoring and breathing sounds, an oximeter to measure blood oxygen levels, and a nasal cannula to monitor air flow.
For more informations on polygraphy equipment, click here.
The sleep diary is a self-assessment tool that patients use to write down, night after night, all sleep-related information (bedtime, sleep latency, waking time, night-time awakenings). It also helps patients gain awareness of their own sleep/wake cycle.
For patients suffering from insomnia, the sleep diary is useful to :
- Gain information on the frequency and severity of insomnia
- Identify factors associated with a good or bad night’s sleep
Additional daytime examinations
Daytime (or alertness) tests
By placing the patient in standardised conditions (no noise, no light, comfortable room temperature), these tests can measure their tendency to fall asleep or, on the contrary, their ability to resist falling asleep. Thus, a distinction is made between :
- The Multiple Sleep Latency Test (MSLT), which measures the severity of sleepiness during the day. The test is repeated five times during the day at two-hour intervals. The patient lies in bed and is instructed to try to fall asleep. Signs of falling asleep in the REM phase (dreams) are used to diagnose possible narcolepsy.
- The Maintenance of Wakefulness Test (MWT), which is carried out under the same conditions as the MSLT, but with the patient seated. This test measures the patient’s ability to resist sleepiness. The MWT is repeated four times during the day at two-hour intervals. The patient is instructed to resist sleep.