Sleepiness measurement

Psychomotor vigilance task performance has also been shown to be sensitive to reduced behavioral alertness associated with obstructive sleep apnea syndrome (OSAS), and the efficacy of interventions for OSAS. Performance of patients with OSAS is impaired on tasks that rely on the ability to sustain attention (85,86). As a measure of behavioral alertness, PVT performance has been demonstrated to be a sensitive method for assessing the attentional capability of patients with OSAS (32,87,88). Kribbs and colleagues (89) found that PVT performance and sleepiness, measured by the MSLT, both reflected the benefits of CPAP use (reduction in respiratory events during sleep). Similarly, the PVT has been used to demonstrate the positive effects of modafinil (a wake-promoting compound) on the capacity to sustain attention in a group of OSAS patients (34). 

Figure 7 PVT reaction times prior to the first uncontrolled sleep attack during total sleep deprivation. Fourteen subjects completed 42 hr of total sleep deprivation and completed a 20-min PVT every 2 hr (represented by the closed circles) 19 subjects completed 88 hr of total sleep deprivation and completed a 10-min PVT every 2 hr (represented by the open circles). The number of test bouts (up to 30) prior to an uncontrolled sleep attack (failure to respond for 30 sec on the PVT) is represented on the bottom abscissa, with time prior to the sleep attack (up to 6 min) represented on the top abscissa. In both subject groups a progressive decline in performance on the visual PVT was evident within minutes of an uncontrolled sleep attack on console. This study also demonstrated an increase in subjective sleepiness (measured using the Stanford Sleepiness Scale) in the test bouts prior to the one in which the first sleep attack occurred. Taken together, these findings suggest that even a very sleepy subject cannot fall asleep while performing computerized tasks without some levels of awareness. (From Ref. 95.)...

One could reasonably believe that complaining of chronic daytime somnolence is a major risk for traffic accidents. Surprisingly, studies on patients suffering from chronic daytime somnolence (9,10) failed to find a link between the risk of traffic accidents and sleepiness measured on a behavioral scale (i.e., Epworth Sleepiness Scale). This could be explained by the fact that subjective questionnaires do not correlate with objective measures of daytime vigilance (11). Another possible explanation could be that sleepiness is dangerous only when perceived during at risk activities. 

SSRIs and the benzodiazepine alprazolam are often used to treat panic disorder. Pharmacokinetic reactions between them could therefore be important. Alprazolam is metabolized by CYP3A4, which fluvoxamine inhibits (SEDA-22, 13). In 23 out-patients (11 men, 12 women, mean age 39 years) who took alprazolam both as monotherapy (mean dose 1.0 mg/day) and in combination with fluvoxamine (mean dose 34 mg/day), fluvoxamine increased plasma alprazolam concentrations by 58% (97). This was not associated with increased sleepiness, measured by a subjective rating scale, but objective measures of psychomotor function were not carried out and these could have been impaired by raised alprazolam concentrations. 

Measurement of sleepiness (via ESS) and RLS symptoms should be completed at each visit to track progress with therapy. 

A straightforward way to measure air quality is to measure the carbon dioxide concentration, which is a natural biological metabolite and increases especially in rooms filled with people. An increase in C02 is mainly responsible for sleepiness and could therefore serve as a direct measure of poor air quality. The base concentration of C02 in the ambient air is around 400 ppm. In non-ventilated rooms the C02-concentration can amount to more than 1000 ppm. Some carbon dioxide concentrations and limits and their impact on human comfort are listed in Tab. 5.4. 

Clyde Mood Scale. The Clyde Mood Scale test may be used as either a self-rated or observer-rated scale. It contains 48 items to measure mood and has been shown to be sensitive to medicine effects. The test takes 5 to 15 minutes to complete and measures the immediate present in a patient or normal individual. The test gives six scores friendly, aggressive, clear-thinking, sleepy, unhappy, and dizzy. 

Dement WC. Objective measurements of daytime sleepiness and performance comparing quazepam with flurazepam in two adult populations using the multiple sleep latency test. J Clin Psychiatry 1991 52(suppl 9) 31-37. 

To understand this principle, consider two examples (1) the natural time-window for sleep readiness, and (2) the natural time-window for hallucinatory activity. These are important to recognize if we wish either to promote sleep and/or to reduce hallucinosis. Some people suppose that they can fall asleep at any time, others that they can fall asleep only at one particular time. Both groups are wrong. Despite wide individual variation in sleep proneness—as measured by the multiple sleep latency test—there are both windows of opportunity (the mid to late afternoon) and forbidden zones (the mid evening) for sleep that affect all of us. I am sleepy now at 4 15 p.m., but four hours from now (at 8 15... 

A visual analog scale can be used for sleepiness, and is similar to what is commonly used in the assessment of pain. It typically uses a horizontal line (e.g., 10 cm), on which subjects can draw a vertical mark indicating their degree of alertness or sleepiness. In theory this provides a continuous measure, rather than a discrete integer. This is probably overly simplistic to measure a multidimensional and complex phenomenon like sleepiness. It does not add much to simple history taking, and is overall rarely used (3,4). 

Other (less specific) scales have also been used as part of the evaluation of EDS. The basic Nordic Sleep Questionnaire (24) is a quantitative measure of subjective sleep complaints not limited to sleepiness. It focuses on events that happen (during sleep or wakefulness), and grades them on a five-point scale from 1 (never) to 5 (almost every day/night). Thus it is best suited for events but not for sleepiness as such. The Sleep Disorders Questionnaire (SDQ) (25) was extracted from another comprehensive questionnaire, the Sleep Questionnaire and Assessment of Wakefulness (SQAW) of Stanford, but is more geared for the diagnosis of specific sleep disorders (e.g., sleep apnea, narcolepsy) than for the evaluation and quantification of EDS. 

It is important for clinicians and researchers alike to know whether they should rely on objective or subjective measures of sleepiness, or both, and how the two types of measures relate to each other. Since sleep latency on the MSLT is considered the gold standard for objective measure and grading of sleepiness, studies have used this as the objective gold standard. However, not all subjective scales have been studied. Several investigators have reported weak or no association between sleep latency and subjective scales such as the Stanford Sleepiness Scale (26-29). The SWAI, or more specifically its EDS subscale, appears to reli-... 

The lack of association, or weak correlation, between subjective scales and objective measures suggests that subjective and objective measures evaluate different aspects of sleepiness. This is the prevailing view (15,30,31,35,36), and it is supported by the association between the ESS, nocturnal sleep latency (on polysomnogram), and respiratory disturbance index (12). 

Danker-Hopfe H, Rraemer S, Dom H, Schmidt A, Ehlert I, Herrmann WM. Time-of-day variations in different measures of sleepiness (MSLT, pupillography, and SSS) and their interrelations. Psychophysiology 2001 38 828-835. 

Rosenthal L, Roehr TA, Roth T. The sleep-wake activity inventory a self-report measure of daytime sleepiness. Biol Psychiatry 1993 34 810-820. 

Weaver TE, Laizner AM, Evans LK, Maislin G, Chugh DK, Lyon K, Smith PL, Schwartz AR, Redhne S, Pack AI, Dinges DF. An instrument to measure functional status outcomes for disorders of excessive sleepiness. Sleep 1997 20 835-843. 

Johns MW. A new method of measuring sleepiness the Epworth Sleepiness Scale. Sleep 1991 14 540-545. 

Johns MW. Sleepiness in different situations measured by the Epworth Sleepiness Scale. Sleep 1994 17 703-710. 

Sangal RB, Sangal JM, Belisle C. MWT and ESS measure different abilities in 41 patients with snoring and daytime sleepiness. Sleep Res 1997 26 493. 

Hamish MJ, Chard SR, Qrr WC. Relationship between measures of objective and subjective sleepiness. Sleep Res 1996 25 492. 

The MSLT has also been used for assessment of other types of compounds that may affect diurnal somnolence. Antihistamines, for example, are commonly associated with subjective sleepiness. Roehrs et al. (58) showed that certain types of antihistamines increase sleepiness, with the MSLT used as the objective measure, while other types do not. 

The MSLT is the most common method of objectively measuring daytime sleepiness in sleep laboratories. This test has been standardized into a form that reliably measures sleepiness in various populations. The MSLT has been used to evaluate levels of sleepiness (1) in conditions of sleep deprivation, reduction, fragmentation, and extension (2) in suspected narcoleptic patients (3) in patients with various disorders of excessive daytime sleepiness (4) in patients with insomnia and (5) in the posttreatment condition of patients with sleep disorders associated with daytime sleepiness. Further work is needed to compare subjective measures of sleepiness and newer performance measures with the MSLT. 

Richardson GS, Carskadon MA, Flagg W, et al. Excessive daytime sleepiness in man multiple sleep latency measurement in narcoleptic and control subjects. Electroencephalog Clin Neurophysiol 1978 45 621-627. 

Carskadon MA, Dement WC, Mitler MM, Roth T, Westbrook PR, Keenan S. Guidelines of the Multiple Sleep Latency Test (MSLT) a standard measure of sleepiness. Sleep 1986 9(4) 519-524. 

Bonnet MH, Arand DL. Sleepiness as measured by modified multiple sleep latency testing varies as a function of preceding activity. Sleep 1998 21 477-483. 

Home JA, Wilkinson S. Chronic sleep reduction daytime vigilance performance and EEG measures of sleepiness, with particular reference to practice effects. Psychophysiology 1985 22 69-78. 

Maislin G, Pack AI, Samuel S, Dinges DF. Objectively measured sleep behaviors and vigilance in community residing elderly with and without complaints of daytime sleepiness. Sleep 2001 24S A224. 

We are using the term inadequate sleep instead of sleep deprivation in our title for a number of reasons. First, few studies have aimed specifically to deprive children or adolescents of sleep. We describe some research on experimental sleep restriction in children but most of these studies fall far short of common deprivation paradigms in animals or even adult humans. Instead, most research in younger humans has assessed outcome measures such as school grades, self-reported sleepiness, and so forth as a function of variations in self-selected or usual sleep patterns with the expectation that children and adolescents who obtain lower than normal amounts of sleep will manifest deficits. Thus, inadequate sleep is defined by sleep characteristics of a sample. We also wanted to note some of the literature on sleep that is disturbed or disrupted due to disease processes such as apnea or periodic leg movements the duration of sleep in sleep disorders may or may not be shortened or restricted although it is likely fragmented and otherwise abnormal. We decided on the term inadequate sleep with the hope that it would encompass these different areas of concern. 

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