Excessive daytime sleepiness (EDS) is defined as the inability to stay awake and alert during major waking episodes of the day, resulting in unintended lapses into drowsiness or sleep,. Severity can be quantified using scales such the Epworth Sleepiness Scale and objectively using the multiple sleep latency test (MSLT) and mean wakefulness test (MWT). These measures though are poorly correlated to each other and clinical judgment is necessary.