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STUDY OBJECTIVES To review the Maintenance of Wakefulness Test (MWT) as assessment of daytime sleepiness in the evaluation of treatment effects and driving fitness in central disorders of hypersomnolence (CDH). METHODS We performed a scoping review of studies using the MWT in patients with CDH (i.e. narcolepsy types 1 and 2, and idiopathic hypersomnia). N=20 articles were included, comprising 683 patients and 129 controls. MWT effect sizes were compared to the Clinical Global Impression (GCI) scale and the Epworth Sleepiness Scale (ESS). MWT sleep latency was correlated to objective driving performances. The role of motivation was evaluated by comparing MWTs of treatment studies (low motivation) to driving fitness studies (high motivation to stay awake). Healthy controls were compared to norm values. RESULTS MWT and CGI were both impacted by the same treatment, however the MWT has higher effect sizes and was more sensitive to measure these effects. The MWT correlated fairly to moderately (ρ=-.26 to -.56; p≤.05) to objective driving performance. Motivation played a major role on MWT sleep latencies (d=.76 to 1.43; p≤.001). Current norm values may not be valid, as sleep latency may be impacted by age. CONCLUSIONS The MWT's applicability to measure treatment effects in CDH was confirmed, but age-adjusted norm values are needed. For a more complete evaluation of EDS it should be combined with subjective measures. Its reliability for driving fitness evaluation is insufficient, and motivation plays a major role. To predict or monitor driving performance in CDH, valid and easy methods should be developed.