Multiple sleep latency test

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The multiple sleep latency test (MSLT) is a method of device performance diagnostics in sleep medicine and is originally called the "multiple sleep latency test". It is used in the diagnosis of sleep disorders to record daytime sleepiness and in narcolepsy to detect premature REM sleep ( sleep-onset REM periods , SOREMP).

As in the nocturnal polysomnography, the patient or test person lies in a quiet, darkened room with several electrodes connected to measuring devices and should fall asleep. Sensors register whether he is falling asleep. The process consists of four or five rounds with a duration of 20 minutes each at two-hour intervals.

Conducting the investigation

There are recommendations for carrying out this study, which serve to ensure uniform application and comparability.

The examination is carried out in a sleep laboratory because of the measurement technology required . According to the recommendations, the MSLT should consist of five courses at two-hour intervals and begin 90 to 180 minutes after the nocturnal polysomnography has ended . The practitioners should have experience with this test.

To assess the sleep-wake rhythm, a sleep diary is required for the period of one week prior to the MSLT .

The test must be immediately preceded by a single long sleep period, which should include at least 6 hours of sleep in the diagnosis of narcolepsy. The shortened version of the MSLT with four rounds is only meaningful for the diagnosis of narcolepsy if at least two SOREMP have already occurred.

preparation

Stimulants and drugs that suppress REM sleep should be discontinued two weeks prior to MSLT in consultation with your doctor. In the case of drugs, their stimulating or sedating properties must be taken into account.

A light breakfast at least an hour before the first run is recommended. A light lunch is planned after the end of the second round. Stimulating activities will affect the outcome. Therefore, smoking and drinking caffeinated drinks should be avoided within at least 30 minutes before each cycle. Exhaustive physical activity should be avoided completely during the day, other stimulating activities by the patient should also be stopped at least 15 minutes before each session, and unusual exposure to sunlight should be avoided.

Standardized test conditions are crucial for valid results. The bedroom should be completely darkened and quiet during the measurement, and the room temperature should be adjusted to the patient's well-being.

Measurement

In order to keep distractions to a minimum, all actions of those carrying out the exercise and the instructions to the test person are standardized. Before each visit, the test person is asked whether they still need to go to the toilet or whether adjustments are necessary for their well-being. The sensors are then calibrated and the test subject is asked to make certain movements with their eyes. At the beginning of the measurement, the test person is asked to take a comfortable position, lie still, keep his eyes closed and try to fall asleep now. Switching off the light signals the start of the measurement.

Common recording of the MSLT includes electroencephalography (EEG), electrooculography (EOG) for both eyes, electromyography (EMG), and electrocardiogram (EKG).

After one round, the patient should get out of bed. He should be prevented from sleeping until the next round, which usually requires continuous observation by the laboratory staff.

Detection of SOREM in sleep

One of the main tasks of the MSLT in the diagnosis of narcolepsy is to find SOREMP. REM sleep usually doesn't appear until the end of the first sleep cycle . REM latency generally refers to the time between falling asleep and the beginning of the first REM phase. If this REM latency is greatly reduced, it is called SOREMP.

evaluation

Hypnogram of an MSLT session - after a short “lying awake” (W) and several short light sleeps (N1) followed by waking again, sleep in stage N2 and only briefly deep sleep (N3). REM sleep did not occur, the sleep latency is also entered as SL
Hypnogram of a MSLT session with the occurrence of SOREM - four minutes of “lying awake” (W) and three minutes of light sleep (N1) followed immediately by REM sleep (R), from which one then woke up briefly. In addition, sleep latency (SL) and REM latency (RL) are entered

The evaluation of the measurements recorded during the MSLT takes place, as is usual in polysomnography, in 30-second epochs, calculated from the beginning of the respective recording with "light off". The beginning of sleep is the first epoch in which more than 15 seconds of sleep (cumulative, any sleep stages) are determined. If no sleep occurs, the session ends after 20 minutes. Sleep latency is the time until sleep begins. If you missed sleep, 20 minutes are included in the calculation of the mean value of all cycles.

To assess the occurrence of REM sleep, the clinical MSLT is continued for 15 minutes following the first sleep epoch according to the recommendations of the AASM. This duration only depends on the time, regardless of sleep stages. REM latency is the time from the beginning of the first sleep epoch to the beginning of the first REM sleep epoch, regardless of the intermediate sleep stages or possible waking up.

The result includes the following information: for each round, the time of the beginning and end, sleep latency, the total sleep duration and the sleep stages achieved in the rounds , the number of SOREMP and the mean sleep latency as the arithmetic mean of the five rounds.

Deviations from the standard protocol and special features should also be documented and taken into account in the interpretation.

The results are clearly shown in the form of a diagram as a sleep profile (hypnogram) per session.

Framework conditions for implementation

The activity of the patient and test person between the tests has a significant impact on the measured sleep latency, since the physiological arousal can mask the urge to sleep in the measurement. Investigations showed that the latency to sleep after five minutes of “walking” directly before the test compared to 15 minutes of “watching TV” directly before the test was increased by an average of almost six minutes.

Differences to the multiple wakefulness test

Significant differences to the multiple wakefulness test (MWT) consist in the subject's posture (here lying opposite sitting), the support for the posture of the head (here lying on a pillow opposite a neck roll), the eyes (here closed opposite and open), the brightness in the Room (here darkening compared to twilight) as well as the default (here “falling asleep” versus “staying awake”).

A subject's ability to relax quickly can help them fall asleep faster. In healthy people it happens that they regularly fall asleep with a short latency with MSLT and can stay awake with MWT.

application

The MSLT is one of the most popular apparatus-based performance diagnostics in sleep medicine worldwide. It is used to diagnose narcolepsy, to objectify hypersomnias, to diagnose other sleep disorders with increased daytime sleepiness and also to monitor the success of the therapy. It is used to determine the severity of daytime sleepiness, but not for the diagnosis of exclusion in narcolepsy. Tonic activation, sleep latency, tendency to sleep and REM latency are examined. The assessment of daytime sleepiness should not be based solely on the sleep latency in the MSLT, but also on the clinical information.

The occurrence of SOREMP is a diagnostic criterion for narcolepsy. However, SOREM can also be observed in obstructive sleep apnea and other disorders with a reduced proportion of REM sleep, medication that suppresses REM sleep after discontinuing REM sleep, and in pent-up sleep deficits. Recovery sleep then leads to the so-called "REM rebound". The other hypersomnias of central nervous origin do not show an increased number of SOREMP.

The interpretation of patients with chronic circadian rhythm disturbances should consider whether they were tested during the hours when they would typically be asleep.

" Nodding off " (Micro Sleep) is not detected in the standard protocol of the MSLT, as episodes are not recognized under 15 seconds in the evaluation in the intended 30-second epochs.

The MSLT is used directly and regularly in a modified form in sleep research .

Alternatives

To determine the severity of daytime sleepiness, a multitude of methods are used in sleep medicine and other areas, depending on the issue. The multiple wakefulness test (MWT) belongs to the instrument-based diagnosis, the Epworth Sleepiness Scale (ESS), the Stanford Sleepiness Scale (SSS) and many other questionnaires belong to the non-instrumental diagnosis .

The procedures take into account partial aspects of daytime sleepiness to a varying extent.

In the literature there are points of criticism of the MSLT to the effect that the values ​​selected as the limit for pathological sleepiness when the test was created were only defined as the "rule of thumb" and are not based on the determination of a reference range with mean value and standard deviation. When several examinations were evaluated, the results of healthy individuals were partly in areas that, according to the rule of thumb, are already considered pathological. Moreover, the results would not necessarily be transferable to other situations in daily life in which the degree of sleepiness is of real interest. In the case of sleep latency in the MSLT, the measurement is made after lying down in a quiet, darkened bedroom and the request to fall asleep, which eliminates many factors that still influence actual sleep.

history

The MSLT was developed by sleep researchers William C. Dement and Mary Carskadon in the early 1970s . This was related to studies on sleep in the mid-1970s, in which the so-called “90-minute day”, in which an experimental sequence consists of 30 minutes of sleep and 60 minutes of being awake, was considered. It provided information about the underlying rhythm and a distribution of REM sleep that does not depend on the individual sleep cycle. The two-hour interval of the runs, which is still used, had practical reasons, since additional investigations were carried out in between in the research of the time. In addition, it should be avoided that the results are overshadowed by an ultradian 90-minute rhythm of sleep. The 20 minutes for each run should initially simply avoid long and boring tests.

The MSLT was first used in an experimental setting from 1976 to research sleepiness and the tendency to fall asleep. It soon became apparent that sleep onset REM periods can be detected, which is important in connection with narcolepsy.

Individual evidence

  1. ↑ a b Michael R. Littner et al., Standards of Practice Committee of the American Academy of Sleep Medicine: Practice Parameters for Clinical Use of the Multiple Sleep Latency Test and the Maintenance of Wakefulness Test . In: Sleep . Vol. 28, No. 1 , 2005, p. 113-121 , PMID 15700727 (English).
  2. ↑ Donna Arand, Michael Bonnet, Thomas Hurwitz et al: The Clinical Use of the MSLT and MWT . In: Sleep . Vol. 28, No. 1 , 2005, p. 123-144 , PMID 15700728 (English).
  3. ↑ Michael H. Bonnet, Donna L. Arand: Sleepiness as Measured by Modified Multiple Sleep Latency Testing Varies as a Function of Preceding Activity . In: Sleep . Vol. 21, No. 5 , 1998, pp. 477-483 , PMID 9703587 (English).
  4. ^ Murray W. Johns: Sensitivity and specificity of the multiple sleep latency test (MSLT), the maintenance of wakefulness test and the Epworth sleepiness scale: Failure of the MSLT as a gold standard . In: Journal of Sleep Research . Vol. 9, No. 1 , 2000, pp. 5–11 , doi : 10.1046 / j.1365-2869.2000.00177.x , PMID 10733683 (English).
  5. ↑ Cornelia Sauter, Heidi Danker-Hopfe: Multiple Sleep Latency Test . In: Somnology . 2013, doi : 10.1007 / s11818-012-0598-1 (English).
  6. ↑ a b S3 guideline for non-restful sleep / sleep disorders of the German Society for Sleep Research and Sleep Medicine (DGSM). In: AWMF online (as of 2009)
  7. ^ S1 guideline for narcolepsy of the German Society for Neurology (DNG). In: AWMF online (as of 2008)
  8. ↑ a b Shannon S. Sullivan, Clete A. Kushida: Multiple Sleep Latency Test and Maintenance of Wakefulness Test . In: Chest . Vol. 134, No. 4 , 2008, p. 854–861 , doi : 10.1378 / chest.08-0822 (English).
  9. ↑ Azmeh Shahid, Kate Wilkinson, Shai Marcu, Colin M. Shapiro: STOP, THAT and One Hundred Other Sleep Scales . Springer, New York 2012, ISBN 978-1-4419-9892-7 , doi : 10.1007 / 978-1-4419-9893-4 .
  10. ^ Murray W. Johns: Daytime sleepiness, snoring, and obstructive sleep apnea. The Epworth Sleepiness Scale . In: Chest . Vol. 103, No. 1 , 1993, p. 30–36 , doi : 10.1378 / chest.103.1.30 (English).
  11. ↑ a b Murray W. Johns: Sensitivity and specificity of the multiple sleep latency test (MSLT), the maintenance of wakefulness test and the Epworth sleepiness scale: Failure of the MSLT as a gold standard . In: Journal of Sleep Research . tape 9 , no. 1 , 2000, pp. 5–11 , doi : 10.1046 / j.1365-2869.2000.00177.x , PMID 10733683 (English).
  12. ^ Mary A. Carskadon, Wiliam C. Dement: Sleep tendency: an objective measure of sleep loss . In: Sleep Research . Vol. 6, No. 1 , 1977, pp. 200-207 (English).
  13. ↑ Lamia Afifi, Clete A. Kushida: Clinical Neurophysiology of Sleep Disorders . Ed .: Christian Guilleminault (=  Handbook of Clinical Neurophysiology ). Elsevier, New York 2005, ISBN 978-0-444-51517-9 , Multiple sleep latency test, pp. 51-57 .
  14. ^ Mary A. Carskadon, William C. Dement, Merrill M. Mitler, Thomas Roth, Philip R. Westbrook, Sharon Keenan: Guidelines for the multiple sleep latency test (MSLT): A standard measure of sleepiness . In: Sleep . tape 9 , no. 4 , 1986, pp. 519-524 , PMID 3809866 (English).
  15. ↑ Merrill M. Mitler, Johanna Van den Hoed, Mary A. Carskadon, Gary Richardson, Richard Park, Christian Guilleminault, William C. Dement: REM sleep episodes during the multiple sleep latency test in narcoleptic patients . In: Electroencephalography and Clinical Neurophysiology . Vol. 46, No. 4 , 1979, p. 479-481 , doi : 10.1016 / 0013-4694 (79) 90149-4 (English).