Clinical UM Guideline

Subject:Multiple Sleep Latency Testing (MSLT) and Maintenance of Wakefulness Testing (MWT)
Guideline #:  CG-MED-43Current Effective Date:  04/07/2015
Status:ReviewedLast Review Date:  02/05/2015


This document addresses multiple sleep latency testing (MSLT) which involves measurement of the time interval from the onset of a nap to the onset of actual sleep, as monitored by electroencephalography (EEG) during a series of short naps.  This document also addresses maintenance of wakefulness testing (MWT) which measures the ability to stay awake for a defined period of time, (generally a 40 minute protocol is used), with the first epoch of sleep as the definition of sleep onset.

For information related to other technologies utilized in the management of sleep-related disorders, please see:

Clinical Indications


Multiple sleep latency testing (MSLT) is considered medically necessary for the evaluation of Narcolepsy or suspected Idiopathic Hypersomnia when the individual being evaluated has excessive daytime sleepiness or disrupted nocturnal sleep of greater than 8 weeks duration and one or more of the following:

  1. Symptoms of narcolepsy, such as cataplexy, sleep paralysis, hypnagogic hallucinations, or hypnopompic hallucinations are present; OR
  2. Obstructive Sleep Apnea (OSA) has been ruled out by polysomnography; OR
  3. OSA has been diagnosed but symptoms persist despite adequate treatment with Positive Airway Pressure Therapy.

Not Medically Necessary:

MSLT is considered not medically necessary in the following four situations:

Maintenance of wakefulness testing (MWT) is considered not medically necessary for the evaluation, diagnosis or assessment of response to therapy for sleep disorders.


The following codes for treatments and procedures applicable to this guideline are included below for informational purposes. Inclusion or exclusion of a procedure, diagnosis or device code(s) does not constitute or imply member coverage or provider reimbursement policy. Please refer to the member's contract benefits in effect at the time of service to determine coverage or non-coverage of these services as it applies to an individual member. 

95805Multiple sleep latency testing (MSLT) or maintenance of wakefulness testing (MWT), recording, analysis, and interpretation of physiological measurements of sleep during multiple trials to assess sleepiness
ICD-9 Diagnosis[For dates of service prior to 10/01/2015]
327.10-327.19Organic disorder of excessive somnolence (organic hypersomnia)
327.43Recurrent isolated sleep paralysis
347.00-347.11Narcolepsy, with or without cataplexy
780.53Hypersomnia with sleep apnea, unspecified
780.54Hypersomnia, unspecified
ICD-10 Diagnosis[For dates of service on or after 10/01/2015]
F51.11-F51.19Hypersomnia not due to a substance or known physiological condition
G47.411-G47.429Narcolepsy and cataplexy
G47.53Recurrent isolated sleep paralysis
Discussion/General Information

The available evidence in the medical literature is sufficient to recommend the use of multiple sleep latency testing (MSLT) with polysomnography (PSG) for the diagnosis of narcolepsy or suspected idiopathic hypersomnia. According to the American Academy of Sleep Medicine (AASM) Practice Parameters for Clinical Use of the Multiple Sleep Latency Test (MSLT) and the Maintenance of Wakefulness Test (MWT), "MSLT is indicated as part of the evaluation of individuals with suspected narcolepsy to confirm the diagnosis, because the co-occurrence of obstructive sleep apnea (OSA) syndrome and narcolepsy is well documented in the published literature."  This AASM paper states further that, "MSLT may be indicated as part of the evaluation of patients with suspected idiopathic hypersomnia to help differentiate idiopathic hypersomnia from narcolepsy" (Littner, 2005).  The 2009 updated AASM Clinical Guideline for the Evaluation, Management and Long-term Care of Obstructive Sleep Apnea in Adults made the following comments about MSLT testing:

MSLT is not routinely indicated in the initial evaluation and diagnosis of OSA or in an assessment of change following treatment with nasal CPAP. However, if excessive sleepiness continues despite optimal treatment, the patient may require an evaluation for possible narcolepsy, including MSLT (Guideline) (Epstein, 2009).

While there is sufficient evidence to recommend that PSG be done prior to an MSLT, there is not adequate information regarding how soon after PSG the MSLT may be done.  For the sake of convenience, it is common practice for the MSLT to be done immediately following the PSG and, if not possible, the MSLT should be done within a reasonable time afterward.  However, the use of MSLT as the sole diagnostic tool or performed routinely, in addition to PSG, for the diagnosis of sleep apnea or for sleepiness associated with conditions other than narcolepsy or idiopathic hypersomnia, is not supported by evidence in the medical literature.

An MSLT consists of four or five nap opportunities to determine both severity of sleepiness and presence of sleep onset rapid eye movement (REM) periods.  The presence of sleep onset REM (also known as SOREM) in a nap, as well as the number of naps in which sleep onset REM is detected, are recorded as well.  For correct interpretation, the MSLT must be performed following an all-night PSG.  The individual is given the opportunity to nap at scheduled intervals for 20 minutes.  Sleep is monitored and the sleep onset (if sleep occurs) is determined by the first EEG appearance of any stage of sleep, including stage 1 sleep.  The sleep latency is the time interval from the onset of the nap to the onset of sleep on the monitored EEG.  The mean sleep latency is then determined by calculating the mean of the sleep latencies of the nap opportunities.

An individual receiving an MSLT should first undergo a PSG to determine if an MSLT is needed.  The MSLT may be performed immediately following, or at some time shortly after, a PSG study.  During an MSLT, the individual has various sensors attached to their body, and they are encouraged to fall asleep.  Once asleep, the individual is aroused several times and then allowed to fall back to sleep.  The time it takes for the individual to fall back to sleep is used as an indicator of various sleep disorders.  Depending upon the results of the test, a diagnosis may be determined.

The utility of maintenance of wakefulness testing (MWT), in terms of improved health outcomes, has not been established. The 2005 AASM Practice Parameters (Littner, 2005) note there are no standard or generally accepted guidelines for the performance of an MWT, and several variations in protocol exist, based on differences in definitions of sleep onset, trial duration and the need for previous night PSG.  Normative data, sensitivity and specificity data, in various tested groups, are also lacking.  Nevertheless, one suggested use has been testing an individual's ability to stay awake when public or personal safety issues are involved.  However, the predictive value of MWT in this setting has not been established, and test results may not translate into behavior in workplace situations.  Another potential use might be assessing the response to various treatments for disorders, such as sleep apnea or narcolepsy.  However there are no established levels to indicate what represents a significant change in the test findings.  Also, it is unclear that testing would provide useful information, over and above the individual's clinical response to therapy in these disorders, or would influence clinical decision-making, thereby improving health outcomes.  The AASM concludes:

Future research is needed to define normative values using rigorous methods, to identify the impact of a standard clinical protocol for MWT, and to correlate the degree of sleepiness on objective testing with safety and occupational risks for the individual and for society in 'real life' circumstances (Littner, 2005).


Apnea-Hypopnea Index (AHI) or Respiratory Disturbance Index (RDI): A measure of apnea severity defined by the total number of episodes of apnea or hypopnea during a full period of sleep divided by the number of hours asleep.  For the purposes of this document, the terms AHI and RDI are interchangeable, although they may differ slightly in clinical use. An AHI/RDI greater than 30 is consistent with severe OSA. In some cases, respiratory effort-related arousals (or RERAS) are included in the RDI value. These RERA episodes represent EEG arousals associated with increased respiratory efforts but do not qualify as apneic or hypopneic episodes because of the absence of their defining air flow changes and/or levels of oxygen desaturation.

Cataplexy: This term refers to transient muscle weakness, sometimes resulting in facial droop or falls, which is often triggered by emotional episodes, such as laughing, crying or anger. It is almost always associated with narcolepsy (see below).

Circadian rhythm disorders: Refers to disruptions in a person's circadian rhythm, which is a term for the "internal body clock" that regulates the 24-hour cycle of biological processes, such as brain wave activity, hormone production, and cell regeneration. Shift work sleep disorders (see definition below) is one of the causes of circadian rhythm disorders.

Excessive daytime sleepiness: This refers to a condition where a person feels very drowsy during the day, even after getting adequate night time rest, and has a tendency to fall asleep or requires extra effort to avoid sleeping in inappropriate situations, such as at work or driving.  This condition is also defined as a score greater than or equal to 10 on the Epworth Sleepiness Scale.

Hypnagogic hallucinations: Vivid, often frightening visual, tactile, or auditory hallucinations that occur as the individual is falling asleep. Hypnopompic hallucinations are similar hallucinations that occur upon awakening.

Idiopathic hypersomnia: This term refers to excessive sleep in the absence of a psychological or physiological cause.  Hypersomnia differs from narcolepsy (see below) in that the sleep does not have a sudden onset and does not involve loss of muscle tone (cataplexy) which is associated with narcolepsy.

Maintenance of Wakefulness Test (MWT): This is a laboratory-based test intended to measure the physiological sleep tendency under standardized conditions in the absence of external alerting factors.  The MWT measures the ability to stay awake for a defined period of time, (generally a 40 minute protocol is used), with the first epoch of sleep as the definition of sleep onset.

Multiple Sleep Latency Test (MSLT): This is a test used in conjunction with PSG to determine the presence and severity of sleepiness.  During this test, the subject is given the opportunity to take naps at specified time intervals.  The test consists of four or five nap opportunities at two hour intervals.  Each nap opportunity is 20 minutes in duration.  Individuals with excessive daytime sleepiness may fall asleep almost immediately, while those without excessive sleepiness may not fall asleep at all.  Severe sleepiness is usually associated with an MSLT mean sleep latency of less than 5 minutes.  The presence of sleep onset rapid eye movement (REM) and the number of naps in which sleep REM occurs are also determined.

Narcolepsy: This refers to a neurological condition, where individuals experience profound daytime sleepiness, which may also include sudden, periodic, and transient loss of muscle tone associated with extreme emotions, such as laughter or anger (cataplexy).

Obstructive sleep apnea (OSA): This is a form of sleep disturbance, which occurs as the result of a physical occlusion of the upper airway during sleep, which interferes with normal breathing.  The occlusion is usually in the back of the tongue and/or flabby tissue in the upper airway.  This condition is associated with frequent awakening and often with daytime sleepiness. According to the American Academy of Sleep Medicine (AASM), updated definitions of OSA severity are provided as follows:

Mild OSA: AHI of 5-15 Involuntary sleepiness during activities that require little attention, such as watching TV or reading;
Moderate OSA: AHI of 15-30 Involuntary sleepiness during activities that require some attention, such as meetings or presentations;
Severe OSA: AHI of more than 30 Involuntary sleepiness during activities that require more active attention, such as talking or driving (AASM, 2008).

Shift work sleep disorder (SWSD): A sleep disorder that is related to unusual or constantly changing work schedules and results in symptoms of insomnia or excessive sleepiness.

Sleep disorder: A disruptive pattern of sleep that may include difficulty falling or staying asleep, falling asleep at inappropriate times, excessive total sleep time, or abnormal behaviors associated with sleep.

Sleep paralysis: Inability to move for one or two minutes immediately after awakening or just before falling asleep.


Peer Reviewed Publications:

  1. Aldrich MS, Chervin RD, Malow BA. Value of the multiple sleep latency test (MSLT) for the diagnosis of narcolepsy. Sleep. 1997; 20(8):620-629.
  2. Banks S, Barnes M, Tarquinio N, et al.  Factors associated with maintenance of wakefulness test mean sleep latency in patients with mild or moderate obstructive sleep apnea and normal subjects.  J Sleep Res. 2004; 13(1):71-78.
  3. Banks S, Catcheside P, Lack LC, et al.  The Maintenance of Wakefulness Test and driving simulator performance.  Sleep, 2005; 28(11):1381-1385.
  4. Berry RB, Hill G, Thompson L, McLaurin V.  Portable monitoring and autotitration versus polysomnography for the diagnosis and treatment of sleep apnea.  Sleep. 2008; 31(10):1423-1431.
  5. Blackwell T, Ancoli-Israel S, Redline S, et al. Factors that may influence the classification of sleep-wake by wrist actigraphy: the MrOS Sleep Study. J Clin Sleep Med. 2011; 7(4):357-367.
  6. Bonnet MH. The MSLT and MWT should not be used for the assessment of workplace safety. J Clin Sleep Med. 2006; 2(2):128-131. 
  7. Chesson AL Jr, Ferber RA, Fry JM, et al. The indications for polysomnography and related procedures. Sleep. 1997; 20(6):423-487.
  8. D'Andrea LA.   Diagnostic studies in the assessment of pediatric sleep-disordered breathing: techniques and indications. Pediatr Clin North Am. 2004; 51(1):169-186.
  9. Fletcher EC, Stich J, Yang KL. Unattended home diagnosis and treatment of obstructive sleep apnea without polysomnography. Arch Fam Med. 2000; 9(2):168-174.
  10. Flemons WW. Clinical practice. Obstructive sleep apnea. N Engl J Med. 2002; 347(7):498-504.
  11. Guilleminault C, Abad VC. Obstructive sleep apnea syndromes. Med Clin North Am. 2004; 8(3):611-630.
  12. Kushida CA, Efron B, Guilleminault C.  A predictive morphometric model for the obstructive sleep apnea syndrome. Ann Intern Med. 1997; 127(8 Pt 1):581-587. 
  13. Mulgrew AT, Fox N, Ayas NT, Ryan CF. Diagnosis and initial management of obstructive sleep apnea without polysomnography: a randomized validation study. Ann Intern Med. 2007; 146(3):157-166.
  14. Olejniczak PW, Fisch BJ. Sleep Disorders. Med Clin North Am. 2003; 87(4):803-833.
  15. Silber MH. Sleep Disorders. Neurol Clin. 2001; 19(1):173-186.
  16. Wichniak A, Geisler P, Tracik F, et al. The influence of polysomnography on the Multiple Sleep Latency Test and other measures of daytime sleepiness. Physiol Behav. 2002; 75(1-2):183-188.
  17. Young T, Skatrud J, Peppard PE. Risk factors for obstructive sleep apnea in adults. JAMA. 2004; 291(16):2013-2016.

Government Agency, Medical Society, and Other Authoritative Publications:

  1. American Academy of Sleep Medicine. Practice parameters for the use of portable monitoring devices in the investigation of suspected obstructive sleep apnea in adults.  Sleep. 2003; 26(7):907-913.
  2. American Academy of Sleep Medicine. Standards of Practice Committee:  Practice parameters for clinical use of the multiple sleep latency tests and the maintenance of wakefulness test (sleepiness; hypersomnia; daytime wakefulness). Sleep. 2005; 28(1):113-121.
  3. American Academy of Sleep Medicine (AASM). Obstructive Sleep Apnea. 2008. Available at: Accessed on January 7, 2015.
  4. American Academy of Sleep Medicine (AASM). Standards for Accreditation of Out of Center Sleep Testing (OCST) in Adult Patients. 2011. Available at: Accessed on January 7, 2015.
  5. American Sleep Disorders Association. A Position Paper: Guidelines for the clinical use of the Multiple Sleep Latency Test. Sleep. 1992; 15(3):268-276. 
  6. American Sleep Disorders Association, Standards of Practice Committee. Practice parameter for the use of portable recording of the assessment of obstructive sleep apnea. Sleep. 1994; 17(4):372-377.
  7. Balk EM, Moorthy D, Obadan NO, et al.  Diagnosis and Treatment of Obstructive Sleep Apnea in Adults.  Comparative Effectiveness Review No. 32. (Prepared by Tufts Evidence-based Practice Center under Contract No. 290-2007-100551). AHRQ Publication No. 11-EHC052-EF. Rockville, MD: Agency for Healthcare Research and Quality. July 2011. Available at: Accessed on January 7, 2015.
  8. Blue Cross and Blue Shield Assoc. Technology Evaluation Center (TEC) assessments. Portable sleep studies for the diagnosis of obstructive sleep apnea syndrome. 1996; 11(2).
  9. Canadian Agency for Drugs and Technologies in Health (CADTH). Portable Monitoring Devices for Diagnosis of Obstructive Sleep Apnea at Home: Review of Accuracy, Cost-Effectiveness, Guidelines, and Coverage in Canada. December 2009. Available at:  Accessed on January 7, 2015.
  10. Centers for Medicare and Medicaid Services. National Coverage Determination for Sleep Testing for Obstructive Sleep Apnea. NCD #240.4.1. Effective March 3, 2009. Available at: Accessed on January 7, 2015.
  11. Chesson AL Jr, Berry RB, Pack A. Practice parameters for the use of portable monitoring devices in the investigation of suspected obstructive sleep apnea in adults. A joint project sponsored by the American Academy of Sleep Medicine, the American Thoracic Society, and the American College of Chest Physicians.  Sleep. 2003, 26(7):907-913.
  12. Collop NA, Anderson WM, Boehlecke B, et al. Portable Monitoring Task Force of the American Academy of Sleep Medicine. Clinical guidelines for the use of unattended portable monitors in the diagnosis of obstructive sleep apnea in adult patients. J Clin Sleep Med. 2007; 3(7):737-747. Available at: Accessed on January 7, 2015.
  13. Epstein LJ, Kristo D, Strollo PJ, et al. Clinical guideline for the evaluation, management and long-term care of obstructive sleep apnea in adults. J Clin Sleep Med. 2009; 5(3):263-276. Available at: Accessed on January 7, 2015.
  14. Flemons WW, Littner MR, Rowley JA, et al.  Home diagnosis of sleep apnea: a systematic review of the literature. An evidence review cosponsored by the American Academy of Sleep Medicine, the American College of Chest Physicians, and the American Thoracic Society. Chest. 2003; 124(4):1543-1579.
  15. Iber C, Ancoli-Israel S, Chesson AL, Quan SF. The AASM manual for the scoring of sleep and associated events: rules, terminology and technical specifications. Westchester, IL: American Academy of Sleep Medicine; 2007. 
  16. Littner MR, Kushida C, Wise M, et al. American Academy of Sleep Medicine Report: Practice parameters for clinical use of the multiple sleep latency test and the maintenance of wakefulness test.  Standards of Practice Committee of the American Academy of Sleep Medicine.  2005 update intended to replace the 1992 Position Paper of the American Sleep Disorders Association on the Clinical Use of the Multiple Sleep Latency Test.  Sleep. 2005; 28(1):113-121.
  17. Marcus CL, Brooks LJ, Draper KA, et al.  American Academy of Pediatrics (AAP).  Diagnosis and Management of Childhood Obstructive Sleep Apnea Syndrome. Pediatrics. 2012; 130:576-584. Available at: Accessed on January 7, 2015.
  18. Trikalinos TA, Ip S, Raman G, et al. Home diagnosis of obstructive sleep apnea-hypopnea syndrome. AHRQ Technology Assessment Program. Agency for Healthcare Research and Quality (AHRQ), Rockville, MD; August 8, 2007. Available at: Accessed on January 7, 2015.
Websites for Additional Information
  1. Journal of the American Medical Association. Patient Page. Breathing Problems during Sleep. JAMA. 2001; 285(22):2936. Available at: Accessed on January 7, 2015.
  2. National Heart, Lung and Blood Institute (NHLBI). Information about Sleep Disorders. Available at: Accessed on January 7, 2015.

Maintenance of Wakefulness Testing (MWT)
Multiple Sleep Latency Testing (MSLT)
Obstructive Sleep Apnea (OSA)
Sleep Disorders

The use of specific product names is illustrative only. It is not intended to be a recommendation of one product over another, and is not intended to represent a complete listing of all products available.

Reviewed02/05/2015Medical Policy & Technology Assessment Committee (MPTAC) review. Definitions and References were updated.
Revised02/13/2014MPTAC review. Medically necessary criteria added to define when MSLT testing is indicated. Definitions and Coding sections were updated. 



MPTAC review. Initial document development.  Position statements and criteria were taken from former policy statements within MED.00002 Selected Sleep Testing Services.