Patients are often referred to sleep disorder centers with a suspicion of a rare sleep disorder, such as narcolepsy, due to their EDS, when in fact a more commonplace issue is to blame. Clinical history taking is paramount, in order to best distinguish amongst the potential causes of hypersomnia. General sleep questionnaires can then help guide the clinician in understanding symptom patterns and severity.

After an initial visit with the clinician, most patients complaining of hypersomnia should be given a sleep diary to complete. The sleep diary is an instrument in which the patient would keep track their daily sleep patterns. Information may include medications taken, bedtime, time to sleep onset, number of awakenings, time of waking, time out of bed, and length and timing of any naps. A sleep diary should typically be used for 1–2 weeks, but it may also be used as a long-term method of assessing a patient’s sleep time, particularly as behaviorally induced insufficient sleep is a common cause of daytime sleepiness. It is worth considering that insufficient sleep may be quite subtle; a loss of 30–60 min of sleep per weekday may induce chronic mild sleep deprivation, from which some patients may be clearly symptomatic. A sample sleep diary is provided in Fig. 2.1; another example is available on the Internet, referenced in Table 2.2.

A nonspecific assessment of the effect of sleep disorders on the lives of patients may be performed by the Short Form 36 (SF-36), a 36-question survey with “an 8-scale profile of functional health and well-being scores as well as psychometrically-based physical and mental health summary measures and a preference-based health utility index” [3]. This questionnaire has been used to assess many medical disorders, including many sleep disorders. The SF-12, a shorter, one-page form, is also available and has been used in sleep research [4].

The most widely used questionnaire specifically for daytime sleepiness is the Epworth Sleepiness Scale (ESS), developed in 1991 by Dr. Murray Johns. In research studies, the ESS has been shown to be reliable when testing and retesting individuals over time. The ESS assesses a patient’s self-report of sleepiness by asking about eight different situations and the likelihood of a patient dozing in each of them. The Likert response scale ranges from 0 (“would never doze”) to 3 (“high chance of dozing”). Adding the results from each question determines a total score that measures subjective sleep propensity “in recent times.” Early research demonstrated that ESS scores greater than 15 were observed in patients with narcolepsy, idiopathic hypersomnolence, or moderate/severe OSA. Since the ESS is easy to use, it has been commonly used in research studies; however conflicting results exist regarding the ability of the ESS to predict objective measures of daytime sleepiness [5, 6]. These results suggest that in practice, the ESS is best used to assess subjective sleepiness in a standardized manner though it is unlikely to replace objective testing. Tracking ESS scores longitudinally for individual patients does appear useful in assessing change or treatment response over weeks to months.

The Stanford Sleepiness Scale (SSS) provides an instantaneous subjective measure of sleepiness as a single question on a seven-point scale [7, 8]. The scale ranges from “feeling active, vital, alert, or wide awake” (1 on the scale) to “no longer fighting sleep, sleep onset soon, or having dreamlike thoughts” (7 on the scale). This scale, in contrast to the ESS, can be used by the same patient many times in 1 day to help track sleep drive. However, this scale becomes less meaningful over longer time periods (weeks to months), since many factors can impact an instantaneous measure of daytime sleepiness. The Karolinska Sleepiness Scale (KSS) is very similarly designed, with the primary difference being that it has a nine-point scale instead of seven [9]. Both of these immediate-assessment sleep scales are validated with objective sleep measures including EEG and performance [10, 11].

The impact of daytime sleepiness on activities of daily living can be assessed by the Functional Outcomes of Sleep Questionnaire (FOSQ). The FOSQ was designed at a fifth grade reading level, is designed to take 15 min to complete, and contains 74 questions over six domains (orientation, physical independence, mobility, occupation, social integration, and economic self-sufficiency), as well as assessment of several additional daily endeavors potentially affected by daytime sleepiness. Initially, this questionnaire was validated to discriminate between normal subjects and those seeking medical attention for a sleep problem [12]. It has since been shown to change with positive pressure therapy for OSA [13], treatment with modafinil [14], and with other treatments of OSA [15]. A modified short form of the FOSQ, the FOSQ-10, has also been validated and may be easier for clinical use in following patients over time [16].

OSA is a disorder of repetitive collapse of the upper airway causing oxygen desaturations and electroencephalographic arousals. Fairly common in the general population (4 % of middle-aged men and 2 % of middle-aged women based on one study) [17], OSA has been demonstrated to increase risk for developing hypertension, heart disease, and cardiovascular disease [18]. Primary symptoms of OSA include snoring, sleep disruption, and most relevant to this chapter, EDS.

The Berlin Questionnaire is one of the more frequently used clinical screening tools for the assessment of OSA: The Berlin Questionnaire was an outcome of the Conference on Sleep in Primary Care, which involved 120 U.S. and German pulmonary and primary care physicians and was held in April 1996 in Berlin, Germany. Questions were selected from the literature to elicit factors or behaviors that, across studies, consistently predicted the presence of sleep–disordered breathing [19]. The questionnaire has three sections. Section one evaluates symptoms including snoring and witnessed apneas, section two covers daytime sleepiness severity, and section three assesses the presence of hypertension and calculates a body mass index. In section 1, high risk was defined as persistent symptoms (3–4 times/week) in two or more questions about their snoring. In section 2, high risk was defined as persistent (3–4 times/week) sleepiness. In section 3, high risk was defined as a history of high blood pressure or a body mass index (BMI) more than 30 kg/m². When two of the three sections meet the criteria for high risk, the patient is at high risk for OSA [20]. While many questionnaires are completed solely by the patient, this questionnaire may require clinician input for the BMI calculation or to supply blood pressure status.

Initially, the STOP-BANG Questionnaire was developed as a short preoperative assessment used by anesthesiologists to screen for OSA. The tool covers similar content as the Berlin Questionnaire, containing eight questions in two sections (the tool was originally designed as STOP only; BANG was added at a later date in an attempt to improve specificity). The name of the questionnaire is developed from the primary content of each question, including s noring, t iredness, o bserved apneas, blood p ressure, BMI, a ge, n eck circumference, and g ender. While the questions on snoring, tiredness, apneas, high blood pressure, age (over 50 years) and gender are straightforward for patients to complete, questions on BMI (more than 35 kg/m²) and neck circumference (greater than 40 cm) often require clinician interaction. A positive answer to three or more questions gives a high probability of OSA [21]. Thus, the STOP-BANG tool is easier to score than the Berlin Questionnaire, but similarly requires some clinical measurements.

While subjective testing for sleep disorders has the advantages of being quick and inexpensive, objective testing is generally considered to be the gold standard. Objective testing removes the possibility of reporting biases and allows for an improved assessment of the patient’s symptom severity. Objective testing of EDS may include overnight polysomnography, out-of-center sleep tests, multiple sleep latency tests (MSLTs), maintenance of wakefulness tests (MWTs), and actigraphy.