SUMMARYThe regulation of wakefulness is important for high-order organisms. Its dysregulation is involved in the pathomechanism of several psychiatric disorders. Thus, a tool for its objective but little time-consuming assessment would be of importance. The Vigilance Algorithm Leipzig allows the objective measurement of sleep propensity, based on a single resting state electroencephalogram. To compare the Vigilance Algorithm Leipzig with the standard for objective assessment of excessive daytime sleepiness, a four-trial Multiple Sleep Latency Test in 25 healthy subjects was conducted. Between the first two trials, a 15-min, 25-channel resting electroencephalogram was recorded, and Vigilance Algorithm Leipzig was used to classify the sleep propensity (i.e. type of vigilance regulation) of each subject. The results of both methods showed significant correlations with the Epworth Sleepiness Scale (q = À0.70; q = 0.45, respectively) and correlated with each other (q = À0.54). Subjects with a stable electroencephalogram-vigilance regulation yielded significant increased sleep latencies compared with an unstable regulation (multiple sleep latency 898.5 s versus 549.9 s; P = 0.03). Further, Vigilance Algorithm Leipzig classifications allowed the identification of subjects with average sleep latencies <6 min with a sensitivity of 100% and a specificity of 77%. Thus, Vigilance Algorithm Leipzig provides similar information on wakefulness regulation in comparison to the much more cost-and time-consuming Multiple Sleep Latency Test. Due to its high sensitivity and specificity for large sleep propensity, Vigilance Algorithm Leipzig could be an effective and reliable alternative to the Multiple Sleep Latency Test, for example for screening purposes in large cohorts, where objective information about wakefulness regulation is needed. IN TROD UCTI ONThe regulation of wakefulness from high alertness to relaxed quiet waking to drowsiness until sleep onset is of fundamental importance for all high-order organisms. This regulation is both a stable individual trait (Tucker et al., 2007;Van Dongen et al., 2005) and dependent on a variety of state factors, such as sleep deficits, recreational drugs and psychopharmacological treatment. Among the medical disorders affecting the wakefulness regulation are sleep disorders, such as narcolepsy (Guilleminault and Brooks, 2001), but also affective disorders and attention deficit hyperactivity disorder (Hegerl and Hensch, 2014).The Vigilance Algorithm Leipzig (VIGALL) has been developed to get an objective parameter of this regulation of wakefulness.