128 The Canadian Journal of CME / March 2004 Focus on CME at

xxx Daytime sleepiness is a common complaint, withpotentially serious consequences. According to the 2001 National Sleep Foundation Poll, 16 % of adults report they are so sleepy during the day that it interferes with their daily activities at least a few days per week.1 Sleepiness negatively impacts memory, mood, concen-tration, work productivity, and psychosocial functioning. Furthermore, excessive sleepiness contributes to the occurrence of automobile collisions and work-related injuries. More than 50,000 motor vehicle collisions per year in the U.S. are attributed to driving while sleepy,2,3 and patients with obstructive sleep apnea have triple the risk of motor vehicle crashes compared to controls.4 It is, therefore, important that the practicing physician have an approach to evaluate and diagnose the patient presenting with excessive somnolence. Sleepiness is best described as an increased physio-logic drive to sleep. This leads to falling asleep unwill-ingly. True sleepiness should be differentiated from physical exhaustion or anhedonia, which are not accom-panied by the need to sleep. Normal individuals who obtain adequate daily sleep should be able to maintain daytime wakefulness with little difficulty. With mild sleepiness, sleep episodes are present during times of rest or when little attention is required. As severity of sleepiness increases, sleep episodes become more fre-quent and occur even during activities that require mod-erate attention. Sleepiness is especially worrisome if the patient falls asleep in active situations, such as during conversations, or while driving or eating. Subjective sleepiness should be quantified using the Epworth Sleepiness Scale. (Table 1).5 The Scale is generated from the responses to a series of eight questions pertaining to patients ’ tendency to fall asleep under various condi-tions. The score ranges from 0 (least sleepy) to 24 (most sleepy). A score of 11 or greater is generally considered abnormal and should prompt further investigation. There are six major causes of excessive daytime sleepiness (Table 2). Multiple causes may be present in a single patient. th