Sleepiness questionnaires

Questionnaires and rating scales for sleepiness can be divided into two broad categories those that estimate short-term, or moment-to-moment fluctuations, and those that assess more long-term (steady-state, permanent) states. The former is typified by the Stanford Sleepiness Scale (SSS), and is best suited for evaluation of sleepiness/alertness throughout the circadian cycle. The latter are typified by the ESS, and are best suited for the evaluation of sleep disorders. 

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. 

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. 

Each subject who showed clear-cut improvement on the MSLT (usually to an optimal score of 20) had obtained substantial extra sleep. Furthermore, almost all of the ratings for these subjects were 1 or 2, with a remarkable increase in the ratings of peak alertness (level 1) over baseline. There was also a notable disappearance of tiredness and sleepiness after lunch. Another very important result of obtaining extra sleep was the dramatic improvement in satiated subjects mood, energy levels, and sense of well-being as indicated by daily checklists and questionnaires. On the other hand, with little or no MSLT improvement, subjective tiredness throughout the day was not reduced, nor were any of the other benefits observed. 

Any sleep evaluation begins with acquiring basic verbal/written information from a person regarding personal health, sleep habits and beliefs, mood, sleep environment, individual satisfaction with sleep and daytime function, fatigue and sleepiness, circadian preferences, and more. Population-validated questionnaires regarding all these variables are usually administered during individual visits with sleep or healthcare... 

Use of rating scales for different symptoms has been also recommended. Dougan et al. (23) developed the motor neurone disease dyspnea rating scale, consisting of 16 questions, each rated on a five-point scale that allows patients with ALS to quantify how dyspnea affects their daily life. This specific questionnaire may be more appropriate for quantifying dyspnea in neuromuscular patients compared with other existing measures, such as the Medical Research Council dyspnea scale (24). Moreover, one of the most commonly used sleepiness scales, the Epworth Sleepiness Scale, may not be as reliable in conditions with such myotonic dystrophy (25). 

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