Sustained difficulty falling asleep or sleeping through the night, intense snoring associated with temporary respiratory arrest can pose severe health risks. Due to insufficient nocturnal rest, severe impairment often also sets in with daytime sleepiness. In specialized medical facilities such as a sleep laboratory, a diagnosis can be made regarding the possible causes and effects by means of elaborate measurement technology.
What is the sleep laboratory?
In a sleep laboratory, electronic measuring devices are used to document specific body functions such as breathing, heart rhythm and body movement throughout the night’s sleep. In a sleep laboratory, electronic measuring devices are used to document special body functions such as breathing, heart rhythm and body movement throughout the night’s sleep. For this purpose, electrodes are attached to many parts of the body. These provide extensive data for storage in a PC as a basis for specialist evaluation. In addition, physical reactions during night sleep, such as leg movements, are recorded by video surveillance. The video surveillance images and the signals from the derived body currents converge in a monitoring and recording room. There, they are monitored by a physician and a sleep lab technician during the entire measurement. For the patient, there is a possibility of contact with the support staff at any time. The recorded measurement data provide information about the different phases of night sleep in further diagnostics. The sleeping and waking times, the intensity and quality of these phases play an important role in the evaluation of the duration and quality of night sleep. The times of so-called breathing pauses and the oxygen content still present during these pauses are also recorded. The measured values are intended to provide clues as to whether organic diseases or other peculiarities are the cause of the sleep deficits. This should reveal therapeutic options.
Function, effect, and goals
Approximately one in ten adults complains of sensitive disturbances in their night’s rest and feel inadequately refreshed after sleep. Such chronic sleep disorders can be examined in more detail at the more than 300 sleep laboratories nationwide. Patients are referred to these specialized facilities who suffer from these serious impairments for a wide variety of reasons. According to the guideline of the German Society for Sleep Research and Sleep Medicine, these include:
- The reasonable suspicion of an organically caused sleep disorder such as, in particular, a sleep apnea syndrome as well as epilepsy or restless legs syndrome (RLS).
- Chronic sleep disorders in which there is no improvement over a period of longer than six months despite conventional therapy
- Severe sleep disorders due to which there is a significant impairment of performance and well-being in the course of the day
- Unusual and unexplained behaviors during nighttime sleep, such as sleepwalking, teeth grinding, abnormal movements, or states of confusion
- Disturbances of the natural sleep-wake rhythm, for example, due to shift work, noise immissions.
- Permanent personal suffering pressure and states of exhaustion.
During a preliminary interview with the patient, first of all, the details of the impairments of night sleep and abnormalities at the time of day are asked. In addition, other important data such as existing diseases, taking medication or known hereditary factors as possible causes or influencing factors for the existing sleep problems are asked. Depending on the symptoms and the scope of the examination, patients spend two to four nights in the sleep laboratory. The aim is to determine the exact nature of the sleep disorder as well as the triggering factors and treatment options. After the examination procedure has been explained to the patient, the necessary wiring of the patient is done by attaching sensors and measuring devices to the body:
- Electrodes attached to the head are to record brain waves, eye movements and movements of the chin muscles.
- A sensor attached to the chest is used to register changes in body position.
- Through the electrodes fixed to the chest, the ECG (electrocardiogram) is recorded.
- To measure the movements triggered by breathing, straps with sensors are attached to the abdomen and chest.
- Snoring sounds are recorded by microphones.
- Movements of the leg muscles are detected by two electrodes on each of the lower legs.
In addition, an infrared video camera is used for constant patient monitoring. The evaluation of all measurements leads to the creation of a sleep profile, in which the course of the respective sleep cycles is shown informative. For the purpose of investigating possible daytime sleepiness, a test procedure on the driving simulator can contribute the next day. This is to determine the patient’s ability to concentrate and react. Depending on the results of all evaluations, therapeutic measures such as wearing a mask at night may be taken.
Risks, side effects, and hazards
While in the sleep laboratory, the patient is presented with an unfamiliar sleep environment. Because of the many straps and cabling by means of sensors attached to the body, the patient must accept a restriction of his otherwise accustomed freedom of movement while lying down. In addition, he must fall asleep aware that he is being observed. There are no uniform patient reactions to this. According to the surveys, some patients sleep worse than at home, especially during the first night. For other patients, however, the unaccustomed sleeping situation does not have a disturbing effect. Risks or health impairments are not known beyond that in the context of an investigation in the sleep laboratory. Especially in case of a detected daytime sleepiness there is an urgent need for therapeutic action. Particularly in connection with driving motor vehicles or working on technical machines during professional practice, there are considerable dangers. In quite a few cases, microsleep at the wheel is still the cause of serious or even fatal traffic accidents. In this context, pedestrians who are considerably affected by daytime sleepiness can also be the cause of accidents. Necessary treatment measures, such as wearing a mask at night to improve sleep quality, must therefore be implemented without delay. To optimize the measurement results in the sleep laboratory, it is advisable for the patient to abstain from caffeinated beverages during the day before the first nocturnal examination. In addition, the diet on this day should not be particularly stressful for night sleep. The reasons for severely disturbed sleep over a prolonged period of time can be varied and cause significant health effects. Therefore, the possibilities of a more detailed examination with the special methods of a sleep laboratory should definitely be taken advantage of.
