The Clinical Use of the MSLT and MWT

Abstract

The studies examined in this review indicate that the MSL is sensitive to conditions expected to increase sleepiness. MSL are generally lower following sleep loss, following use of sedating medications, during wakefulness in the late night or early morning hours, and among patients with sleep disorders associated with excessive sleepiness such as narcolepsy or obstructive sleep apnea. However, the wide range in MSL makes it difficult to establish a specific threshold value for excessive sleepiness or to discriminate patients with sleep disorders from non-patients. Some of this variation may be attributable to methodological differences and some may be attributable to individual differences in sleep tendency (e.g., related to age). The studies analyzed in this review indicate that the MSL on both the MSLT and MWT does not discriminate well between patients with sleep disorders and normal populations. This is due to large SD as well as floor or ceiling effects in the tests. However, the MSL shows appropriate change from initial testing to subsequent testing following treatment or manipulations intended to alter sleepiness or alertness. Additionally the presence of two or more SOREMPs on the MSLT is a common finding in narcolepsy patients. However, SOREMPs are not exclusive to narcolepsy patients but are frequent in untreated sleep apnea

Fatigue estimation using voice analysis

“…The SOL is measured from lights out to the first minute of stage 1 sleep. Significant correlations often found between the length of sleep loss and sleep latency gives face validity for using sleep onset latency as a biologically based measure of sleepiness (Arand, Bonnet, Hurwitz, Mitler, Rosa, & Sangal, 2005).…”

Naps-MS

“…The morning after the overnight PSG, patients underwent MSLT. 4 The mean sleep latency of each of the four or five naps and whether REM sleep was observed were reported.…”

“…1-3 Excessive sleepiness is defined as sleepiness occurring in a situation when an individual is expected to be awake and alert. 4 Fatigue is defined as a subjective lack of physical or mental energy that is perceived by the individual or caregiver to interfere with usual and desired activities. 5 Sleepiness and fatigue, although often occurring in the same patient, can exist independently, and either can negatively impact quality of life in MS. 3 The etiology of these symptoms has not been completely elucidated, although studies have shown that sleep disturbances are associated with a higher incidence of fatigue and daytime sleepiness.…”

Objective measures of sleepiness

“…However, this test has undergone further tests of validity, and the test is criticized for lack of a standardized protocol. 10,11 …”

“…MSLT criteria for narcolepsy are: mean sleep latency shorter than 5 minutes or 2 or more REM episodes in five naps. 10,11,13 …”