Chapter 3 - Assessment of daytime sleepiness
Introduction
Excessive daytime sleepiness (EDS) is a common symptom of insufficient sleep, inadequate sleep, intrinsic sleep disorders, and many other medical conditions. Defined as “a subjective report of difficulty in maintaining the alert, awake state,” sleepiness becomes excessive when it occurs during inappropriate settings (American Academy of Sleep Medicine, 2001).
Patients who suffer from EDS are common in the practices of primary care physicians, many types of specialists, and particularly sleep medicine specialists. To provide an appropriate diagnosis and effective treatment options, careful assessment by history, physical examination, and other approaches is often necessary. Repeated assessments may be necessary to track changes in EDS and response to treatment over time.
Perhaps in part because it is nearly a universal experience, sleepiness is often ignored or minimized by patients. A National Sleep Foundation poll in 2002 suggested that 37% of adults are so sleepy during the day that it interferes with their daily activities a few days a month or more; 16% experience this level of daytime sleepiness a few days a week or more. Fifty-one percent of the polled subjects reported driving while drowsy, and 17% have dozed off while driving. Increased subjective daytime somnolence and chronically disrupted sleep also have been associated with an increase in estimated healthcare use (Kapur et al., 2002).
People with chronically insufficient or inadequate sleep may have many complaints other than “sleepiness,” such as fatigue, lack of energy, and tiredness. Though patients may not distinguish between these expressions, clinicians may find some utility in encouraging patients to be more specific. Synonyms for sleepiness may be useful, such as drowsiness, tendency to fall asleep, and decreased alertness; additional terms for fatigue are weariness, weakness, and depleted energy (Pigeon et al., 2003). Sleep disorders such as obstructive sleep apnea or narcolepsy are often thought to be associated primarily with EDS. However, patients with sleep apnea often complain more about lack of energy than EDS (Chervin, 2000). Attempting to compare alternative definitions of sleepiness, Rinaldi et al. (2001) assessed tiredness, resistible sleepiness, irresistible sleepiness, and sleep attacks by questionnaire in a group of patients referred for complaints of daytime sleepiness or possible sleep-disordered breathing. Findings demonstrated that sleep attacks and irresistible sleepiness were more specific and sensitive for short mean sleep latencies on formal testing than tiredness or resistible sleepiness.
Section snippets
History
Some patients ask to be evaluated for EDS, but many patients, after years of suffering from sleepiness, do not realize that this state is not normal. Falling asleep at work or during social activities can become commonplace for some individuals who may not come to attention unless persuaded to seek help by friends, significant others, or near-miss motor vehicle crashes. Such patients may require detailed inquiry to elicit symptoms of EDS. Areas to explore include the length of time patients
Physical Examination
Frequently, the physical examination of the patient with EDS reveals no specific findings. Patients with severe sleepiness may fall asleep in a waiting room or nod off during a lull in conversation. Other behavioral signs of sleepiness may include yawning, ptosis, reduced activity, lapses in attention, and head-nodding (Roehrs et al., 2000). Dark or baggy circles under the eyes are often thought to represent a sign of sleepiness, but few studies have been performed to evaluate, confirm, or
Subjective Testing
Several standardized methods for assessment of daytime sleepiness exist, but the most commonly used is the Epworth Sleepiness Scale (ESS) (Table 3.3). The ESS evaluates a patient’s self-report of sleepiness by asking about the likelihood of a patient dozing in eight different sedentary situations. The Likert response scale ranges from 0 (“would never doze”) to 3 (“high chance of dozing”). The sum of the eight item responses then quantifies subjective sleep propensity “in recent times” (Johns,
Nocturnal Polysomnography
The overnight polysomnogram often plays a central role in the diagnostic process. Findings that may help assess the severity of EDS include a short sleep latency and increased sleep efficiency. In a study of 147 referred patients, the only factor among demographic information, polysomnographic data, and subjective assessments that was found to correlate significantly with mean sleep latency on the MSLT was sleep latency on overnight polysomnography (Chervin et al., 1995). Arousals or hypoxia
Multiple Sleep Latency Test
The MSLT is considered the standard, for objective assessment of EDS, to which all other measures are compared. Developed by Carskadon & Dement in the 1970s at Stanford University, this test was described as a test of physiological sleep tendency. The MSLT measures the speed with which a patient is able to fall asleep in a controlled environment at time points spread throughout the day (Carskadon and Dement, 1977). The guidelines for the tests were later revised in 1986 and some pretest
Maintenance of Wakefulness Test
The Maintenance of Wakefulness Test (MWT) is a variation of the MSLT designed to assess an individual’s ability to remain awake during sleep-inducing circumstances. The patient, seated in bed within a dimly lit and quiet room, is told to “sit still and remain awake” rather than to “try to fall asleep,” as in an MSLT. As initially described, the subject is monitored for sleep onset during five sessions, each lasting 20 or 40 minutes, scheduled at 2-hour intervals, beginning 2 hours after
Other Testing
Pupillometry measures the spontaneous variation of the pupil diameter and the pupillary light reflex. Sleepiness-related alterations in spontaneous pupil behavior in a dark environment were described by Lowenstein & Loewenfeld in 1958. Later, Yoss et al. (1969) discovered pupillary changes in patients with narcolepsy. More recent studies have confirmed these earlier reports, and have attempted to increase the objectivity of pupillometry (Wilhelm et al., 1998). Increase in spontaneous pupil
Practical Applications
Although most patients referred to a sleep disorders clinic have a chief complaint of EDS, assessment of this problem by a careful history is usually sufficient to estimate the severity and impact. Most of the diagnostic challenge centers on the determination of underlying causes. An ESS can provide a quick, inexpensive, and repeatable quantification of subjective sleepiness. A nocturnal polysomnogram is often indicated to identify root causes for abnormal sleepiness, when such causes are not
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