Pictorial Sleepiness Scale

Maldonado et al. (11) sought to develop a nonverbal sleepiness scale that could be used to test young children or poorly educated adults. Subject groups were asked to rank in order seven cartoon faces designed to depict different sleepiness levels. Results were used to transform rankings into linear measures that eliminated two faces. A new subject group ranked the remaining five cartoons and a scale was constructed. The scale correlated significantly with KSS and SSS when tested in groups of normal control adults, sleep apnea patients, shift workers, and school children. The authors envision using this scale clinically and for research. It remains to be seen whether this scale will gain popularity.

Profile of Mood States

As the name implies, the profile of mood states (POMS) was originally designed to assess mood (12). However, over the years POMS gained significant popularity among sleep researchers. Ironically, early versions of the test included a dimension for sleepiness that was eliminated as part of psychometric test purification (because it was not an independent factor). Sleepiness loads several subscales, including Vigor (negative), Confusion, and Fatigue. The Confusion scale appears to be responsive to severe sleepiness while the Vigor scale may be more responsive to partial sleep deprivation (13). Similarly, subscales of the Medical Outcomes Study Short Form-36 (SF-36) have been used to assess sleepiness, particularly in drug trials.

Visual Analog Scales and Side Effect Checklists

Any number of visual analog scales and side effect checklists are available to assess sleepiness (Fig. 2). These tests are popular because of their simplicity, ease of administration, and face validity. Formal validation studies have not been conducted on these tests. However, these types of tests are generally sensitive to changes within an individual in response to an intervention. For example, sleepiness reliably increases in response to sleep deprivation and decreases in response to stimulant administration. Nonetheless, absolute values of the scores are difficult to compare meaningfully across subjects. This limits these tests' utility for clinical purposes.


The three most common methods for indexing physiological sleepiness use: (i) the multiple sleep latency test (MSLT), (ii) pupillometry, and (iii) quantitative electroen-cephalography (EEG) analysis. Measuring sleepiness using physiological indices provides the clinician an objective technique that does not have the disadvantages inherently associated with self-report. Falling asleep represents an involuntary process. Therefore, appraising the biological substrate either during this process or under conditions conducive to falling asleep can minimize psychological, psychiatric, and intentional confounds. However, one should be aware that the results derived from such testing are not necessarily above manipulation by a test subject. In as much as the test procedure relies on cooperation, there is room for intentional alteration, within limits. For example, individuals attempting to prove they are not sleepy may engage in a mental arithmetic task when asked to close their eyes and relax during an

Visual Analog Scale (VAS)

Wide Awake

Dead Tired

FIGURE 2 Example of a visual analog scale.

EEG baseline sample. Physiological measures may be more reliable for demonstrating sleepiness than proving alertness (i.e., if a positive test is one that affirms sleepiness, physiological tests are more prone to false negative than false positive results).

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