Clinical evaluation of the patient with excessive sleepiness

Introduction Sleepiness is defined as a physiologic drive toward sleep. It is a normal process that can occur briefly upon awaking after the major sleep period, after prolonged sustained wakefulness, or when awoken from the middle of one's natural sleep period. The term is often used interchangeably with the words “somnolence” or “drowsiness”. Frequently, patients who complain of sleepiness do not use the word “sleepiness” to describe their symptoms, but use vague terms such as tired, fatigue, no energy, or other similar terminology. As it may affect diagnosis and treatment, the physician should differentiate between fatigue and true sleepiness. Fatigue is a feeling of tiredness that may be both physical and psychological, and it typically occurs in conditions such as depression or multiple sclerosis. Pure fatigue is not associated with significant daytime sleepiness, as there is no physiological drive for sleep, so on lying down sleep does not occur, but instead wakefulness and rest ensues. People may describe themselves being “tired”, “fatigued” or perhaps as “not having enough energy” after a period of physical activity; but sleep does not occur, i.e. the individual would not be sleepy. In a study of 190 obstructive sleep apnea (OSA) patients, only about 47% used the term “sleepiness” to describe their symptoms, while about 62% described themselves as having a “lack of energy”, 61% reported feelings of “tiredness”, and 57% used the term “fatigue”.