Available Diagnostic Methods For Studying Sleepiness, Sleep and Day-Rhythm Disorders
Forms, questionaries and diaries:
Many forms and questionnaires, all scientifically validated, are used to help in the diagnosis and to follow the efficiency of a treatment.
A sleep diary is a self-reported record of an individual's sleeping and waking times with relevant information such as times of meals and environmental factors. It is usually kept during a period of a couple of weeks. It is a very useful tool in the diagnosis and treatment of sleep and day rhythm disorders. A sleep log can also make patients more aware of their sleep quality and the parameters affecting it.
Other diaries are used for instance by nutritionists when implementing weight control programs.
While sleep diaries reflect the subjective perception of the sleep quality actigraphy offers objective and quantitative measurements. It is a method of monitoring patient’s rest/activity cycles. This method is increasingly used in the assessment of patients with sleep disorders, to determine day rhythm activity cycles (circadian rhythm), and to evaluate the effect of a treatment on sleep and day activity.
A wrist-watch-like device (actigraph) records continuously gross movements activity over extended periods of time. Sleep- wake patterns are estimated from periods of activity and inactivity based on this movement. It is also possible to measure environmental variables such as light and temperature.
Actigraphy is used together with sleep diaries.
Ambulatory blood-oxygen monitoring
This method is popular for ambulatory or home studies of breathing disorders using a small pulse oximeter. It is a wristwatch like device, with a sensor placed on the fingertip that indirectly measures the oxygen content in the blood.
Overnight Sleep Studies:
One of the best tools for studying sleep disorder is the overnight sleep study. Sensors are used to monitor various physiological parameters. The study can be more or less detailed.
- For investigating snoring and breathing disorders, a small and easy to handle portable-monitoring system is used, recording a limited number of parameters - airflow, respiratory effort, oxygen content in the blood a "polygraphy" (PG).
- For a more comprehensive investigation of sleep quality the state of the art method is used, the "polysomnography" (PSG). Besides the above mentioned parameters, many other sensors and electrodes collect information reflecting brain and heart activity, muscle tension, eye and body movements.
- For more sophisticated overnight sleep study, especially when unusual behaviour while asleep is expected, infra-red video monitoring is added to the PSG.
All these types of overnight sleep studies can be done at home, in a hotel or at the hospital.
Home sleep study has the advantage for the patient to be in the comfort of his/her own home. Either the patient comes to the Clinic to be instructed about how to use the equipment or a technician goes to the patient’s home to install the apparatus.
Ambulatory recordings are also very useful to rule out seizure activity. The brain electrical activity is continuously monitored during 12, 24 hours or even longer. The Clinic, with its innovative technology, is unique by providing all these facilities including if need be video recording at home together with a complete PSG.
Hospital based sleep studies. When assistance or continuous attendance is required (e.g. to rule out epilepsy or other unusual behaviour, to adjust a breathing supportive equipment or when children are investigated) PSG is done at the Hospital. A sleep technician observes continuously the recording and the video monitoring, reporting any suspect event.
Investigating daytime sleepiness:
Multiple Sleep Latency Tests (MSLT)
This is a multiple naps study, used to find out the level of sleepiness during the day, specially useful for narcolepsy. It indicates how quickly the patient falls asleep during a series short naps in a quiet daytime situation and measures whether the patient enters the stage of dream sleep.
Maintenance of Wakefulness Test (MWT)
This sleep study is used to measure alertness during the day. It shows whether or not the patient is able to stay awake for a defined period of time.
Positive Air Pressure (PAP):
This study is used to set the right air pressure for e.g. CPAP therapy in patients with sleep apnea.
An alternative or compliment to PAP for sleep apnea tratment is the use of oral appliances (dental guard/splint...) which can be provided by our specialists.
Other diagnostic methods:
EEG records the electrical activity of the brain. It is used to detect epilepsy or other abnormalities.
It can be performed either at the Clinic or ambulatory, at home for 24 hours.
Studies of the autonomic nervous system (ANS):
It is often useful to study the "automatic" function of the nervous system such as heart activity during a longer period of time (e.g. to study stress level, reasons for syncope etc...) especially when conventional electrocardyography ruled out heart disorder. 24-48 hours recording can easily be done without disturbing day activities.
The clinic offers also other methods and "wearables" for various ambulatory investigations (day-rhythm monitoring, blood pressure, heart activity etc...).