FROM THE CLINICAL KNOWLEDGE CENTER
Assessment Tools for the Recognition and Diagnosis of the Symptom of Excessive Sleepiness

by Eleanor Roberts, PhD

Excessive sleepiness (ES) comprises difficulty in maintaining wakefulness and increased propensity to fall asleep during inappropriate circumstances; factors that can interfere with many daily activities. The prevalence of ES ranges from approximately 10% to 20% depending on the population and the methodologies used to measure this symptom.(1-3)

Sleep-wake disorders are one of the principal causes of ES and are divided into disorders of circadian misalignment (e.g., shift work disorder), disorders of sleep disruption (e.g., obstructive sleep apnea [OSA], restless leg syndrome [RLS]), and disorders of sleep-wake dysregulation (e.g., narcolepsy). Other causes of ES include poor sleep hygiene, medical or psychiatric conditions, and iatrogenic effects of psychotropic medications. Mood and cognitive alterations associated with sleep deprivation and ES include fatigue, confusion, amotivation, irritability, decreased alertness, memory problems, and trouble concentrating.(4) Physiologic decrements may also arise from sleep loss including hyperalgesia(1) and Type 2 diabetes.(5) Due to this wide range of possible consequences associated with the symptom of ES, clinicians should always inquire about sleep-wake issues during office visits for acute and chronic conditions, as well as during annual physical examinations.

Obtaining a sleep history is a key first step to early identification of sleep-wake problems, yet the frequency of sleep history documentation is low.(6,7) Questions should include those about the quality and quantity of a person’s sleep; how sleepy, drowsy and/or fatigued they are during the day, and how many times such problems occur during the week; whether they have any known associated problems, such as OSA, RLS, or narcolepsy, and what pharmacological and/or behavioral measures they may use to combat any problems. An on-line version of a sleep history questionnaire can be found at http://www.sjo.org/docs/SleepHistoryQuestionnaire.pdf.

The Epworth Sleepiness Scale (ESS) is a self-report questionnaire specifically designed to rate a person’s likelihood of falling asleep in eight different daily situations. These include watching TV or reading, sitting and talking to someone, riding in a car as a passenger, and when stopped in traffic while driving.(8) Scores on individual questions range from 0 (no likelihood of dozing) to 3 (high likelihood of dozing), with a combined score of 10 or greater being indicative of ES. However, the accuracy of the ESS depends upon the patient’s awareness of falling asleep. It has been shown that a person can experience periods of sleep for up to two minutes without realizing it.(9) Hence, items in their medical history should also be investigated if a problem with wakefulness is suspected. A PDF of the ESS prepared by the National Sleep Foundation can be found at http://www.sleepfoundation.org/atf/cf/{F6BF2668-A1B4-4FE8-8D1A-A5D39340D9CB}/epworth_scale.pdf.

It is important to distinguish whether a person is suffering from ES or fatigue. Although both of these symptoms may appear to impact a person similarly, they can stem from a very different set of medical issues, which may thus involve different treatments depending on the symptom. As a general indication, while fatigue intensity can be relieved by merely resting, or by ceasing an activity, ES normally only gets better by having a period of sleep. Validated subjective scales that measure fatigue include the short, self-rated Fatigue Severity Scale (FSS). Questions consist of nine statements, rated on a 7-point Likert scale, regarding family and social interactions; daily activities, and work.(10) This screening tool is sensitive to treatment- and time-dependent changes and can discriminate features of fatigue that arise from different medical conditions. A PDF of the FSS prepared by the National Women’s Resource Center, Inc., can be found at http://www.healthywomen.org/FatigueSeverityScale.pdf.

The sleep-related breathing disorder OSA, which can lead to the symptom of ES, has a low rate of diagnosis and treatment although it affects around 2% of women and 4% of men in the United States.(11-13) The Berlin Questionnaire is a validated, clinician-rated, screening tool that assesses risk for OSA.(14) This questionnaire inquires about snoring, ES, and hypertension. Patients are rated as “High Risk” or “Low Risk”, with the former being considered if two or more categories are positive, which would indicate that a person should be referred for a sleep study that includes examination by overnight polysomnography. An on-line version of the Berlin Questionnaire can be found at http://www.ssc.ca/documents/case_studies/2006/documents/sleep_BQ_e.pdf.

While these assessments can be quickly carried out in the clinical setting, take-home sleep-wake diaries can provide a more detailed examination of a patient’s daily sleep and waking habits. They are valuable diagnostic tools that can pinpoint medical or lifestyle factors causing a sleep complaint, identify insufficient sleep or circadian rhythm disturbances as an etiology of sleepiness, and improve poor sleep habits through patient self-awareness. Typical elements include the time a person goes to bed, the amount of time they take to fall asleep, whether they have any nighttime awakenings, the length of their sleep episodes, their final awakening time, and evaluation of well-being and alertness throughout the day. Note is also taken of consumption of caffeine, nicotine, alcohol and any over-the-counter and/or prescription medications. A PDF of a sleep diary prepared by the National Sleep Foundation can be found at http://www.sleep.buffalo.edu/sleepdiary.pdf.

Finally, to investigate diagnoses of OSA, RLS, or narcolepsy (among others), a patient can be referred to a sleep center. This will normally involve an overnight stay during which a number of measures are taken, including an electroencephalogram, electromyogram and electrooculogram; the patient’s respiration rate and depth, and their oxygen saturation levels – collectively known as polysomnography.(15) During the day a person’s proclivity to sleep can be measured using the Multiple Sleep Latency Test (MSLT), and their ability to stay awake in a quiet, dark situation measured using the Maintenance of Wakefulness Test (MWT).(16,17)

Further details of these assessment tools can be found at the National Sleep Foundation website (http://www.sleepfoundation.org/site/c.huIXKjM0IxF/b.2417141/k.2E30/The_National_Sleep_Foundation.htm), and the American Academy of Sleep Medicine (http://www.aasmnet.org/).

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